diff --git a/src/Util/MIMETypeUtil.h b/src/Util/MIMETypeUtil.h
index 611d509c9..52e950a7c 100644
--- a/src/Util/MIMETypeUtil.h
+++ b/src/Util/MIMETypeUtil.h
@@ -46,6 +46,7 @@ extern NSString *const OWSMimeTypeUnknownForTests;
 + (nullable NSString *)utiTypeForFileExtension:(NSString *)fileExtension;
 + (nullable NSString *)fileExtensionForUTIType:(NSString *)utiType;
 + (nullable NSString *)fileExtensionForMIMEType:(NSString *)mimeType;
++ (nullable NSString *)mimeTypeForFileExtension:(NSString *)fileExtension;
 
 @end
 
diff --git a/src/Util/MIMETypeUtil.m b/src/Util/MIMETypeUtil.m
index 1979e6bab..fa3c5a717 100644
--- a/src/Util/MIMETypeUtil.m
+++ b/src/Util/MIMETypeUtil.m
@@ -398,9 +398,24 @@ NSString *const OWSMimeTypeUnknownForTests = @"unknown/mimetype";
 
 + (nullable NSString *)utiTypeForMIMEType:(NSString *)mimeType
 {
-    CFStringRef utiType
-        = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, (__bridge CFStringRef)mimeType, NULL);
-    return (__bridge_transfer NSString *)utiType;
+    NSString *utiType = (__bridge_transfer NSString *)UTTypeCreatePreferredIdentifierForTag(
+        kUTTagClassMIMEType, (__bridge CFStringRef)mimeType, NULL);
+
+    if (!utiType) {
+        if ([mimeType isEqualToString:@"audio/amr"]) {
+            utiType = @"org.3gpp.adaptive-multi-rate-audio";
+        } else if ([mimeType isEqualToString:@"audio/mp3"] || [mimeType isEqualToString:@"audio/x-mpeg"] ||
+            [mimeType isEqualToString:@"audio/mpeg"] || [mimeType isEqualToString:@"audio/mpeg3"] ||
+            [mimeType isEqualToString:@"audio/x-mp3"] || [mimeType isEqualToString:@"audio/x-mpeg3"]) {
+            utiType = (NSString *)kUTTypeMP3;
+        } else if ([mimeType isEqualToString:@"audio/aac"] || [mimeType isEqualToString:@"audio/x-m4a"]) {
+            utiType = (NSString *)kUTTypeMPEG4Audio;
+        } else if ([mimeType isEqualToString:@"audio/aiff"] || [mimeType isEqualToString:@"audio/x-aiff"]) {
+            utiType = (NSString *)kUTTypeAudioInterchangeFileFormat;
+        }
+    }
+
+    return utiType;
 }
 
 + (nullable NSString *)fileExtensionForUTIType:(NSString *)utiType
@@ -1546,6 +1561,1006 @@ NSString *const OWSMimeTypeUnknownForTests = @"unknown/mimetype";
     return result;
 }
 
++ (nullable NSString *)mimeTypeForFileExtension:(NSString *)fileExtension
+{
+    OWSAssert(fileExtension.length > 0);
+
+    return [self genericExtensionTypesToMIMETypes][fileExtension];
+}
+
++ (NSDictionary *)genericExtensionTypesToMIMETypes
+{
+    static NSDictionary *result = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        result = @{
+            @"123" : @"application/vnd.lotus-1-2-3",
+            @"3dml" : @"text/vnd.in3d.3dml",
+            @"3ds" : @"image/x-3ds",
+            @"3g2" : @"video/3gpp2",
+            @"3gp" : @"video/3gpp",
+            @"7z" : @"application/x-7z-compressed",
+            @"aab" : @"application/x-authorware-bin",
+            @"aac" : @"audio/x-aac",
+            @"aam" : @"application/x-authorware-map",
+            @"aas" : @"application/x-authorware-seg",
+            @"abw" : @"application/x-abiword",
+            @"ac" : @"application/pkix-attr-cert",
+            @"acc" : @"application/vnd.americandynamics.acc",
+            @"ace" : @"application/x-ace-compressed",
+            @"acu" : @"application/vnd.acucobol",
+            @"acutc" : @"application/vnd.acucorp",
+            @"adp" : @"audio/adpcm",
+            @"aep" : @"application/vnd.audiograph",
+            @"afm" : @"application/x-font-type1",
+            @"afp" : @"application/vnd.ibm.modcap",
+            @"ahead" : @"application/vnd.ahead.space",
+            @"ai" : @"application/postscript",
+            @"aif" : @"audio/x-aiff",
+            @"aifc" : @"audio/x-aiff",
+            @"aiff" : @"audio/x-aiff",
+            @"air" : @"application/vnd.adobe.air-application-installer-package+zip",
+            @"ait" : @"application/vnd.dvb.ait",
+            @"ami" : @"application/vnd.amiga.ami",
+            @"apk" : @"application/vnd.android.package-archive",
+            @"appcache" : @"text/cache-manifest",
+            @"application" : @"application/x-ms-application",
+            @"apr" : @"application/vnd.lotus-approach",
+            @"arc" : @"application/x-freearc",
+            @"asc" : @"application/pgp-signature",
+            @"asf" : @"video/x-ms-asf",
+            @"asm" : @"text/x-asm",
+            @"aso" : @"application/vnd.accpac.simply.aso",
+            @"asx" : @"video/x-ms-asf",
+            @"atc" : @"application/vnd.acucorp",
+            @"atom" : @"application/atom+xml",
+            @"atomcat" : @"application/atomcat+xml",
+            @"atomsvc" : @"application/atomsvc+xml",
+            @"atx" : @"application/vnd.antix.game-component",
+            @"au" : @"audio/basic",
+            @"avi" : @"video/x-msvideo",
+            @"aw" : @"application/applixware",
+            @"azf" : @"application/vnd.airzip.filesecure.azf",
+            @"azs" : @"application/vnd.airzip.filesecure.azs",
+            @"azw" : @"application/vnd.amazon.ebook",
+            @"bat" : @"application/x-msdownload",
+            @"bcpio" : @"application/x-bcpio",
+            @"bdf" : @"application/x-font-bdf",
+            @"bdm" : @"application/vnd.syncml.dm+wbxml",
+            @"bed" : @"application/vnd.realvnc.bed",
+            @"bh2" : @"application/vnd.fujitsu.oasysprs",
+            @"bin" : @"application/octet-stream",
+            @"blb" : @"application/x-blorb",
+            @"blorb" : @"application/x-blorb",
+            @"bmi" : @"application/vnd.bmi",
+            @"bmp" : @"image/bmp",
+            @"book" : @"application/vnd.framemaker",
+            @"box" : @"application/vnd.previewsystems.box",
+            @"boz" : @"application/x-bzip2",
+            @"bpk" : @"application/octet-stream",
+            @"btif" : @"image/prs.btif",
+            @"bz" : @"application/x-bzip",
+            @"bz2" : @"application/x-bzip2",
+            @"c" : @"text/x-c",
+            @"c11amc" : @"application/vnd.cluetrust.cartomobile-config",
+            @"c11amz" : @"application/vnd.cluetrust.cartomobile-config-pkg",
+            @"c4d" : @"application/vnd.clonk.c4group",
+            @"c4f" : @"application/vnd.clonk.c4group",
+            @"c4g" : @"application/vnd.clonk.c4group",
+            @"c4p" : @"application/vnd.clonk.c4group",
+            @"c4u" : @"application/vnd.clonk.c4group",
+            @"cab" : @"application/vnd.ms-cab-compressed",
+            @"caf" : @"audio/x-caf",
+            @"cap" : @"application/vnd.tcpdump.pcap",
+            @"car" : @"application/vnd.curl.car",
+            @"cat" : @"application/vnd.ms-pki.seccat",
+            @"cb7" : @"application/x-cbr",
+            @"cba" : @"application/x-cbr",
+            @"cbr" : @"application/x-cbr",
+            @"cbt" : @"application/x-cbr",
+            @"cbz" : @"application/x-cbr",
+            @"cc" : @"text/x-c",
+            @"cct" : @"application/x-director",
+            @"ccxml" : @"application/ccxml+xml",
+            @"cdbcmsg" : @"application/vnd.contact.cmsg",
+            @"cdf" : @"application/x-netcdf",
+            @"cdkey" : @"application/vnd.mediastation.cdkey",
+            @"cdmia" : @"application/cdmi-capability",
+            @"cdmic" : @"application/cdmi-container",
+            @"cdmid" : @"application/cdmi-domain",
+            @"cdmio" : @"application/cdmi-object",
+            @"cdmiq" : @"application/cdmi-queue",
+            @"cdx" : @"chemical/x-cdx",
+            @"cdxml" : @"application/vnd.chemdraw+xml",
+            @"cdy" : @"application/vnd.cinderella",
+            @"cer" : @"application/pkix-cert",
+            @"cfs" : @"application/x-cfs-compressed",
+            @"cgm" : @"image/cgm",
+            @"chat" : @"application/x-chat",
+            @"chm" : @"application/vnd.ms-htmlhelp",
+            @"chrt" : @"application/vnd.kde.kchart",
+            @"cif" : @"chemical/x-cif",
+            @"cii" : @"application/vnd.anser-web-certificate-issue-initiation",
+            @"cil" : @"application/vnd.ms-artgalry",
+            @"cla" : @"application/vnd.claymore",
+            @"class" : @"application/java-vm",
+            @"clkk" : @"application/vnd.crick.clicker.keyboard",
+            @"clkp" : @"application/vnd.crick.clicker.palette",
+            @"clkt" : @"application/vnd.crick.clicker.template",
+            @"clkw" : @"application/vnd.crick.clicker.wordbank",
+            @"clkx" : @"application/vnd.crick.clicker",
+            @"clp" : @"application/x-msclip",
+            @"cmc" : @"application/vnd.cosmocaller",
+            @"cmdf" : @"chemical/x-cmdf",
+            @"cml" : @"chemical/x-cml",
+            @"cmp" : @"application/vnd.yellowriver-custom-menu",
+            @"cmx" : @"image/x-cmx",
+            @"cod" : @"application/vnd.rim.cod",
+            @"com" : @"application/x-msdownload",
+            @"conf" : @"text/plain",
+            @"cpio" : @"application/x-cpio",
+            @"cpp" : @"text/x-c",
+            @"cpt" : @"application/mac-compactpro",
+            @"crd" : @"application/x-mscardfile",
+            @"crl" : @"application/pkix-crl",
+            @"crt" : @"application/x-x509-ca-cert",
+            @"cryptonote" : @"application/vnd.rig.cryptonote",
+            @"csh" : @"application/x-csh",
+            @"csml" : @"chemical/x-csml",
+            @"csp" : @"application/vnd.commonspace",
+            @"css" : @"text/css",
+            @"cst" : @"application/x-director",
+            @"csv" : @"text/csv",
+            @"cu" : @"application/cu-seeme",
+            @"curl" : @"text/vnd.curl",
+            @"cww" : @"application/prs.cww",
+            @"cxt" : @"application/x-director",
+            @"cxx" : @"text/x-c",
+            @"dae" : @"model/vnd.collada+xml",
+            @"daf" : @"application/vnd.mobius.daf",
+            @"dart" : @"application/vnd.dart",
+            @"dataless" : @"application/vnd.fdsn.seed",
+            @"davmount" : @"application/davmount+xml",
+            @"dbk" : @"application/docbook+xml",
+            @"dcr" : @"application/x-director",
+            @"dcurl" : @"text/vnd.curl.dcurl",
+            @"dd2" : @"application/vnd.oma.dd2+xml",
+            @"ddd" : @"application/vnd.fujixerox.ddd",
+            @"deb" : @"application/x-debian-package",
+            @"def" : @"text/plain",
+            @"deploy" : @"application/octet-stream",
+            @"der" : @"application/x-x509-ca-cert",
+            @"dfac" : @"application/vnd.dreamfactory",
+            @"dgc" : @"application/x-dgc-compressed",
+            @"dic" : @"text/x-c",
+            @"dir" : @"application/x-director",
+            @"dis" : @"application/vnd.mobius.dis",
+            @"dist" : @"application/octet-stream",
+            @"distz" : @"application/octet-stream",
+            @"djv" : @"image/vnd.djvu",
+            @"djvu" : @"image/vnd.djvu",
+            @"dll" : @"application/x-msdownload",
+            @"dmg" : @"application/x-apple-diskimage",
+            @"dmp" : @"application/vnd.tcpdump.pcap",
+            @"dms" : @"application/octet-stream",
+            @"dna" : @"application/vnd.dna",
+            @"doc" : @"application/msword",
+            @"docm" : @"application/vnd.ms-word.document.macroenabled.12",
+            @"docx" : @"application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+            @"dot" : @"application/msword",
+            @"dotm" : @"application/vnd.ms-word.template.macroenabled.12",
+            @"dotx" : @"application/vnd.openxmlformats-officedocument.wordprocessingml.template",
+            @"dp" : @"application/vnd.osgi.dp",
+            @"dpg" : @"application/vnd.dpgraph",
+            @"dra" : @"audio/vnd.dra",
+            @"dsc" : @"text/prs.lines.tag",
+            @"dssc" : @"application/dssc+der",
+            @"dtb" : @"application/x-dtbook+xml",
+            @"dtd" : @"application/xml-dtd",
+            @"dts" : @"audio/vnd.dts",
+            @"dtshd" : @"audio/vnd.dts.hd",
+            @"dump" : @"application/octet-stream",
+            @"dvb" : @"video/vnd.dvb.file",
+            @"dvi" : @"application/x-dvi",
+            @"dwf" : @"model/vnd.dwf",
+            @"dwg" : @"image/vnd.dwg",
+            @"dxf" : @"image/vnd.dxf",
+            @"dxp" : @"application/vnd.spotfire.dxp",
+            @"dxr" : @"application/x-director",
+            @"ecelp4800" : @"audio/vnd.nuera.ecelp4800",
+            @"ecelp7470" : @"audio/vnd.nuera.ecelp7470",
+            @"ecelp9600" : @"audio/vnd.nuera.ecelp9600",
+            @"ecma" : @"application/ecmascript",
+            @"edm" : @"application/vnd.novadigm.edm",
+            @"edx" : @"application/vnd.novadigm.edx",
+            @"efif" : @"application/vnd.picsel",
+            @"ei6" : @"application/vnd.pg.osasli",
+            @"elc" : @"application/octet-stream",
+            @"emf" : @"application/x-msmetafile",
+            @"eml" : @"message/rfc822",
+            @"emma" : @"application/emma+xml",
+            @"emz" : @"application/x-msmetafile",
+            @"eol" : @"audio/vnd.digital-winds",
+            @"eot" : @"application/vnd.ms-fontobject",
+            @"eps" : @"application/postscript",
+            @"epub" : @"application/epub+zip",
+            @"es3" : @"application/vnd.eszigno3+xml",
+            @"esa" : @"application/vnd.osgi.subsystem",
+            @"esf" : @"application/vnd.epson.esf",
+            @"et3" : @"application/vnd.eszigno3+xml",
+            @"etx" : @"text/x-setext",
+            @"eva" : @"application/x-eva",
+            @"evy" : @"application/x-envoy",
+            @"exe" : @"application/x-msdownload",
+            @"exi" : @"application/exi",
+            @"ext" : @"application/vnd.novadigm.ext",
+            @"ez" : @"application/andrew-inset",
+            @"ez2" : @"application/vnd.ezpix-album",
+            @"ez3" : @"application/vnd.ezpix-package",
+            @"f" : @"text/x-fortran",
+            @"f4v" : @"video/x-f4v",
+            @"f77" : @"text/x-fortran",
+            @"f90" : @"text/x-fortran",
+            @"fbs" : @"image/vnd.fastbidsheet",
+            @"fcdt" : @"application/vnd.adobe.formscentral.fcdt",
+            @"fcs" : @"application/vnd.isac.fcs",
+            @"fdf" : @"application/vnd.fdf",
+            @"fe_launch" : @"application/vnd.denovo.fcselayout-link",
+            @"fg5" : @"application/vnd.fujitsu.oasysgp",
+            @"fgd" : @"application/x-director",
+            @"fh" : @"image/x-freehand",
+            @"fh4" : @"image/x-freehand",
+            @"fh5" : @"image/x-freehand",
+            @"fh7" : @"image/x-freehand",
+            @"fhc" : @"image/x-freehand",
+            @"fig" : @"application/x-xfig",
+            @"flac" : @"audio/x-flac",
+            @"fli" : @"video/x-fli",
+            @"flo" : @"application/vnd.micrografx.flo",
+            @"flv" : @"video/x-flv",
+            @"flw" : @"application/vnd.kde.kivio",
+            @"flx" : @"text/vnd.fmi.flexstor",
+            @"fly" : @"text/vnd.fly",
+            @"fm" : @"application/vnd.framemaker",
+            @"fnc" : @"application/vnd.frogans.fnc",
+            @"for" : @"text/x-fortran",
+            @"fpx" : @"image/vnd.fpx",
+            @"frame" : @"application/vnd.framemaker",
+            @"fsc" : @"application/vnd.fsc.weblaunch",
+            @"fst" : @"image/vnd.fst",
+            @"ftc" : @"application/vnd.fluxtime.clip",
+            @"fti" : @"application/vnd.anser-web-funds-transfer-initiation",
+            @"fvt" : @"video/vnd.fvt",
+            @"fxp" : @"application/vnd.adobe.fxp",
+            @"fxpl" : @"application/vnd.adobe.fxp",
+            @"fzs" : @"application/vnd.fuzzysheet",
+            @"g2w" : @"application/vnd.geoplan",
+            @"g3" : @"image/g3fax",
+            @"g3w" : @"application/vnd.geospace",
+            @"gac" : @"application/vnd.groove-account",
+            @"gam" : @"application/x-tads",
+            @"gbr" : @"application/rpki-ghostbusters",
+            @"gca" : @"application/x-gca-compressed",
+            @"gdl" : @"model/vnd.gdl",
+            @"geo" : @"application/vnd.dynageo",
+            @"gex" : @"application/vnd.geometry-explorer",
+            @"ggb" : @"application/vnd.geogebra.file",
+            @"ggt" : @"application/vnd.geogebra.tool",
+            @"ghf" : @"application/vnd.groove-help",
+            @"gif" : @"image/gif",
+            @"gim" : @"application/vnd.groove-identity-message",
+            @"gml" : @"application/gml+xml",
+            @"gmx" : @"application/vnd.gmx",
+            @"gnumeric" : @"application/x-gnumeric",
+            @"gph" : @"application/vnd.flographit",
+            @"gpx" : @"application/gpx+xml",
+            @"gqf" : @"application/vnd.grafeq",
+            @"gqs" : @"application/vnd.grafeq",
+            @"gram" : @"application/srgs",
+            @"gramps" : @"application/x-gramps-xml",
+            @"gre" : @"application/vnd.geometry-explorer",
+            @"grv" : @"application/vnd.groove-injector",
+            @"grxml" : @"application/srgs+xml",
+            @"gsf" : @"application/x-font-ghostscript",
+            @"gtar" : @"application/x-gtar",
+            @"gtm" : @"application/vnd.groove-tool-message",
+            @"gtw" : @"model/vnd.gtw",
+            @"gv" : @"text/vnd.graphviz",
+            @"gxf" : @"application/gxf",
+            @"gxt" : @"application/vnd.geonext",
+            @"h" : @"text/x-c",
+            @"h261" : @"video/h261",
+            @"h263" : @"video/h263",
+            @"h264" : @"video/h264",
+            @"hal" : @"application/vnd.hal+xml",
+            @"hbci" : @"application/vnd.hbci",
+            @"hdf" : @"application/x-hdf",
+            @"hh" : @"text/x-c",
+            @"hlp" : @"application/winhlp",
+            @"hpgl" : @"application/vnd.hp-hpgl",
+            @"hpid" : @"application/vnd.hp-hpid",
+            @"hps" : @"application/vnd.hp-hps",
+            @"hqx" : @"application/mac-binhex40",
+            @"htke" : @"application/vnd.kenameaapp",
+            @"htm" : @"text/html",
+            @"html" : @"text/html",
+            @"hvd" : @"application/vnd.yamaha.hv-dic",
+            @"hvp" : @"application/vnd.yamaha.hv-voice",
+            @"hvs" : @"application/vnd.yamaha.hv-script",
+            @"i2g" : @"application/vnd.intergeo",
+            @"icc" : @"application/vnd.iccprofile",
+            @"ice" : @"x-conference/x-cooltalk",
+            @"icm" : @"application/vnd.iccprofile",
+            @"ico" : @"image/x-icon",
+            @"ics" : @"text/calendar",
+            @"ief" : @"image/ief",
+            @"ifb" : @"text/calendar",
+            @"ifm" : @"application/vnd.shana.informed.formdata",
+            @"iges" : @"model/iges",
+            @"igl" : @"application/vnd.igloader",
+            @"igm" : @"application/vnd.insors.igm",
+            @"igs" : @"model/iges",
+            @"igx" : @"application/vnd.micrografx.igx",
+            @"iif" : @"application/vnd.shana.informed.interchange",
+            @"imp" : @"application/vnd.accpac.simply.imp",
+            @"ims" : @"application/vnd.ms-ims",
+            @"in" : @"text/plain",
+            @"ink" : @"application/inkml+xml",
+            @"inkml" : @"application/inkml+xml",
+            @"install" : @"application/x-install-instructions",
+            @"iota" : @"application/vnd.astraea-software.iota",
+            @"ipfix" : @"application/ipfix",
+            @"ipk" : @"application/vnd.shana.informed.package",
+            @"irm" : @"application/vnd.ibm.rights-management",
+            @"irp" : @"application/vnd.irepository.package+xml",
+            @"iso" : @"application/x-iso9660-image",
+            @"itp" : @"application/vnd.shana.informed.formtemplate",
+            @"ivp" : @"application/vnd.immervision-ivp",
+            @"ivu" : @"application/vnd.immervision-ivu",
+            @"jad" : @"text/vnd.sun.j2me.app-descriptor",
+            @"jam" : @"application/vnd.jam",
+            @"jar" : @"application/java-archive",
+            @"java" : @"text/x-java-source",
+            @"jisp" : @"application/vnd.jisp",
+            @"jlt" : @"application/vnd.hp-jlyt",
+            @"jnlp" : @"application/x-java-jnlp-file",
+            @"joda" : @"application/vnd.joost.joda-archive",
+            @"jpe" : @"image/jpeg",
+            @"jpeg" : @"image/jpeg",
+            @"jpg" : @"image/jpeg",
+            @"jpgm" : @"video/jpm",
+            @"jpgv" : @"video/jpeg",
+            @"jpm" : @"video/jpm",
+            @"js" : @"application/javascript",
+            @"json" : @"application/json",
+            @"jsonml" : @"application/jsonml+json",
+            @"kar" : @"audio/midi",
+            @"karbon" : @"application/vnd.kde.karbon",
+            @"kfo" : @"application/vnd.kde.kformula",
+            @"kia" : @"application/vnd.kidspiration",
+            @"kml" : @"application/vnd.google-earth.kml+xml",
+            @"kmz" : @"application/vnd.google-earth.kmz",
+            @"kne" : @"application/vnd.kinar",
+            @"knp" : @"application/vnd.kinar",
+            @"kon" : @"application/vnd.kde.kontour",
+            @"kpr" : @"application/vnd.kde.kpresenter",
+            @"kpt" : @"application/vnd.kde.kpresenter",
+            @"kpxx" : @"application/vnd.ds-keypoint",
+            @"ksp" : @"application/vnd.kde.kspread",
+            @"ktr" : @"application/vnd.kahootz",
+            @"ktx" : @"image/ktx",
+            @"ktz" : @"application/vnd.kahootz",
+            @"kwd" : @"application/vnd.kde.kword",
+            @"kwt" : @"application/vnd.kde.kword",
+            @"lasxml" : @"application/vnd.las.las+xml",
+            @"latex" : @"application/x-latex",
+            @"lbd" : @"application/vnd.llamagraphics.life-balance.desktop",
+            @"lbe" : @"application/vnd.llamagraphics.life-balance.exchange+xml",
+            @"les" : @"application/vnd.hhe.lesson-player",
+            @"lha" : @"application/x-lzh-compressed",
+            @"link66" : @"application/vnd.route66.link66+xml",
+            @"list" : @"text/plain",
+            @"list3820" : @"application/vnd.ibm.modcap",
+            @"listafp" : @"application/vnd.ibm.modcap",
+            @"lnk" : @"application/x-ms-shortcut",
+            @"log" : @"text/plain",
+            @"lostxml" : @"application/lost+xml",
+            @"lrf" : @"application/octet-stream",
+            @"lrm" : @"application/vnd.ms-lrm",
+            @"ltf" : @"application/vnd.frogans.ltf",
+            @"lvp" : @"audio/vnd.lucent.voice",
+            @"lwp" : @"application/vnd.lotus-wordpro",
+            @"lzh" : @"application/x-lzh-compressed",
+            @"m13" : @"application/x-msmediaview",
+            @"m14" : @"application/x-msmediaview",
+            @"m1v" : @"video/mpeg",
+            @"m21" : @"application/mp21",
+            @"m2a" : @"audio/mpeg",
+            @"m2v" : @"video/mpeg",
+            @"m3a" : @"audio/mpeg",
+            @"m3u" : @"audio/x-mpegurl",
+            @"m3u8" : @"application/vnd.apple.mpegurl",
+            @"m4a" : @"audio/mp4",
+            @"m4u" : @"video/vnd.mpegurl",
+            @"m4v" : @"video/x-m4v",
+            @"ma" : @"application/mathematica",
+            @"mads" : @"application/mads+xml",
+            @"mag" : @"application/vnd.ecowin.chart",
+            @"maker" : @"application/vnd.framemaker",
+            @"man" : @"text/troff",
+            @"mar" : @"application/octet-stream",
+            @"mathml" : @"application/mathml+xml",
+            @"mb" : @"application/mathematica",
+            @"mbk" : @"application/vnd.mobius.mbk",
+            @"mbox" : @"application/mbox",
+            @"mc1" : @"application/vnd.medcalcdata",
+            @"mcd" : @"application/vnd.mcd",
+            @"mcurl" : @"text/vnd.curl.mcurl",
+            @"mdb" : @"application/x-msaccess",
+            @"mdi" : @"image/vnd.ms-modi",
+            @"me" : @"text/troff",
+            @"mesh" : @"model/mesh",
+            @"meta4" : @"application/metalink4+xml",
+            @"metalink" : @"application/metalink+xml",
+            @"mets" : @"application/mets+xml",
+            @"mfm" : @"application/vnd.mfmp",
+            @"mft" : @"application/rpki-manifest",
+            @"mgp" : @"application/vnd.osgeo.mapguide.package",
+            @"mgz" : @"application/vnd.proteus.magazine",
+            @"mid" : @"audio/midi",
+            @"midi" : @"audio/midi",
+            @"mie" : @"application/x-mie",
+            @"mif" : @"application/vnd.mif",
+            @"mime" : @"message/rfc822",
+            @"mj2" : @"video/mj2",
+            @"mjp2" : @"video/mj2",
+            @"mk3d" : @"video/x-matroska",
+            @"mka" : @"audio/x-matroska",
+            @"mks" : @"video/x-matroska",
+            @"mkv" : @"video/x-matroska",
+            @"mlp" : @"application/vnd.dolby.mlp",
+            @"mmd" : @"application/vnd.chipnuts.karaoke-mmd",
+            @"mmf" : @"application/vnd.smaf",
+            @"mmr" : @"image/vnd.fujixerox.edmics-mmr",
+            @"mng" : @"video/x-mng",
+            @"mny" : @"application/x-msmoney",
+            @"mobi" : @"application/x-mobipocket-ebook",
+            @"mods" : @"application/mods+xml",
+            @"mov" : @"video/quicktime",
+            @"movie" : @"video/x-sgi-movie",
+            @"mp2" : @"audio/mpeg",
+            @"mp21" : @"application/mp21",
+            @"mp2a" : @"audio/mpeg",
+            @"mp3" : @"audio/mpeg",
+            @"mp4" : @"video/mp4",
+            @"mp4a" : @"audio/mp4",
+            @"mp4s" : @"application/mp4",
+            @"mp4v" : @"video/mp4",
+            @"mpc" : @"application/vnd.mophun.certificate",
+            @"mpe" : @"video/mpeg",
+            @"mpeg" : @"video/mpeg",
+            @"mpg" : @"video/mpeg",
+            @"mpg4" : @"video/mp4",
+            @"mpga" : @"audio/mpeg",
+            @"mpkg" : @"application/vnd.apple.installer+xml",
+            @"mpm" : @"application/vnd.blueice.multipass",
+            @"mpn" : @"application/vnd.mophun.application",
+            @"mpp" : @"application/vnd.ms-project",
+            @"mpt" : @"application/vnd.ms-project",
+            @"mpy" : @"application/vnd.ibm.minipay",
+            @"mqy" : @"application/vnd.mobius.mqy",
+            @"mrc" : @"application/marc",
+            @"mrcx" : @"application/marcxml+xml",
+            @"ms" : @"text/troff",
+            @"mscml" : @"application/mediaservercontrol+xml",
+            @"mseed" : @"application/vnd.fdsn.mseed",
+            @"mseq" : @"application/vnd.mseq",
+            @"msf" : @"application/vnd.epson.msf",
+            @"msh" : @"model/mesh",
+            @"msi" : @"application/x-msdownload",
+            @"msl" : @"application/vnd.mobius.msl",
+            @"msty" : @"application/vnd.muvee.style",
+            @"mts" : @"model/vnd.mts",
+            @"mus" : @"application/vnd.musician",
+            @"musicxml" : @"application/vnd.recordare.musicxml+xml",
+            @"mvb" : @"application/x-msmediaview",
+            @"mwf" : @"application/vnd.mfer",
+            @"mxf" : @"application/mxf",
+            @"mxl" : @"application/vnd.recordare.musicxml",
+            @"mxml" : @"application/xv+xml",
+            @"mxs" : @"application/vnd.triscape.mxs",
+            @"mxu" : @"video/vnd.mpegurl",
+            @"n-gage" : @"application/vnd.nokia.n-gage.symbian.install",
+            @"n3" : @"text/n3",
+            @"nb" : @"application/mathematica",
+            @"nbp" : @"application/vnd.wolfram.player",
+            @"nc" : @"application/x-netcdf",
+            @"ncx" : @"application/x-dtbncx+xml",
+            @"nfo" : @"text/x-nfo",
+            @"ngdat" : @"application/vnd.nokia.n-gage.data",
+            @"nitf" : @"application/vnd.nitf",
+            @"nlu" : @"application/vnd.neurolanguage.nlu",
+            @"nml" : @"application/vnd.enliven",
+            @"nnd" : @"application/vnd.noblenet-directory",
+            @"nns" : @"application/vnd.noblenet-sealer",
+            @"nnw" : @"application/vnd.noblenet-web",
+            @"npx" : @"image/vnd.net-fpx",
+            @"nsc" : @"application/x-conference",
+            @"nsf" : @"application/vnd.lotus-notes",
+            @"ntf" : @"application/vnd.nitf",
+            @"nzb" : @"application/x-nzb",
+            @"oa2" : @"application/vnd.fujitsu.oasys2",
+            @"oa3" : @"application/vnd.fujitsu.oasys3",
+            @"oas" : @"application/vnd.fujitsu.oasys",
+            @"obd" : @"application/x-msbinder",
+            @"obj" : @"application/x-tgif",
+            @"oda" : @"application/oda",
+            @"odb" : @"application/vnd.oasis.opendocument.database",
+            @"odc" : @"application/vnd.oasis.opendocument.chart",
+            @"odf" : @"application/vnd.oasis.opendocument.formula",
+            @"odft" : @"application/vnd.oasis.opendocument.formula-template",
+            @"odg" : @"application/vnd.oasis.opendocument.graphics",
+            @"odi" : @"application/vnd.oasis.opendocument.image",
+            @"odm" : @"application/vnd.oasis.opendocument.text-master",
+            @"odp" : @"application/vnd.oasis.opendocument.presentation",
+            @"ods" : @"application/vnd.oasis.opendocument.spreadsheet",
+            @"odt" : @"application/vnd.oasis.opendocument.text",
+            @"oga" : @"audio/ogg",
+            @"ogg" : @"audio/ogg",
+            @"ogv" : @"video/ogg",
+            @"ogx" : @"application/ogg",
+            @"omdoc" : @"application/omdoc+xml",
+            @"onepkg" : @"application/onenote",
+            @"onetmp" : @"application/onenote",
+            @"onetoc" : @"application/onenote",
+            @"onetoc2" : @"application/onenote",
+            @"opf" : @"application/oebps-package+xml",
+            @"opml" : @"text/x-opml",
+            @"oprc" : @"application/vnd.palm",
+            @"org" : @"application/vnd.lotus-organizer",
+            @"osf" : @"application/vnd.yamaha.openscoreformat",
+            @"osfpvg" : @"application/vnd.yamaha.openscoreformat.osfpvg+xml",
+            @"otc" : @"application/vnd.oasis.opendocument.chart-template",
+            @"otf" : @"application/x-font-otf",
+            @"otg" : @"application/vnd.oasis.opendocument.graphics-template",
+            @"oth" : @"application/vnd.oasis.opendocument.text-web",
+            @"oti" : @"application/vnd.oasis.opendocument.image-template",
+            @"otp" : @"application/vnd.oasis.opendocument.presentation-template",
+            @"ots" : @"application/vnd.oasis.opendocument.spreadsheet-template",
+            @"ott" : @"application/vnd.oasis.opendocument.text-template",
+            @"oxps" : @"application/oxps",
+            @"oxt" : @"application/vnd.openofficeorg.extension",
+            @"p" : @"text/x-pascal",
+            @"p10" : @"application/pkcs10",
+            @"p12" : @"application/x-pkcs12",
+            @"p7b" : @"application/x-pkcs7-certificates",
+            @"p7c" : @"application/pkcs7-mime",
+            @"p7m" : @"application/pkcs7-mime",
+            @"p7r" : @"application/x-pkcs7-certreqresp",
+            @"p7s" : @"application/pkcs7-signature",
+            @"p8" : @"application/pkcs8",
+            @"pas" : @"text/x-pascal",
+            @"paw" : @"application/vnd.pawaafile",
+            @"pbd" : @"application/vnd.powerbuilder6",
+            @"pbm" : @"image/x-portable-bitmap",
+            @"pcap" : @"application/vnd.tcpdump.pcap",
+            @"pcf" : @"application/x-font-pcf",
+            @"pcl" : @"application/vnd.hp-pcl",
+            @"pclxl" : @"application/vnd.hp-pclxl",
+            @"pct" : @"image/x-pict",
+            @"pcurl" : @"application/vnd.curl.pcurl",
+            @"pcx" : @"image/x-pcx",
+            @"pdb" : @"application/vnd.palm",
+            @"pdf" : @"application/pdf",
+            @"pfa" : @"application/x-font-type1",
+            @"pfb" : @"application/x-font-type1",
+            @"pfm" : @"application/x-font-type1",
+            @"pfr" : @"application/font-tdpfr",
+            @"pfx" : @"application/x-pkcs12",
+            @"pgm" : @"image/x-portable-graymap",
+            @"pgn" : @"application/x-chess-pgn",
+            @"pgp" : @"application/pgp-encrypted",
+            @"pic" : @"image/x-pict",
+            @"pkg" : @"application/octet-stream",
+            @"pki" : @"application/pkixcmp",
+            @"pkipath" : @"application/pkix-pkipath",
+            @"plb" : @"application/vnd.3gpp.pic-bw-large",
+            @"plc" : @"application/vnd.mobius.plc",
+            @"plf" : @"application/vnd.pocketlearn",
+            @"pls" : @"application/pls+xml",
+            @"pml" : @"application/vnd.ctc-posml",
+            @"png" : @"image/png",
+            @"pnm" : @"image/x-portable-anymap",
+            @"portpkg" : @"application/vnd.macports.portpkg",
+            @"pot" : @"application/vnd.ms-powerpoint",
+            @"potm" : @"application/vnd.ms-powerpoint.template.macroenabled.12",
+            @"potx" : @"application/vnd.openxmlformats-officedocument.presentationml.template",
+            @"ppam" : @"application/vnd.ms-powerpoint.addin.macroenabled.12",
+            @"ppd" : @"application/vnd.cups-ppd",
+            @"ppm" : @"image/x-portable-pixmap",
+            @"pps" : @"application/vnd.ms-powerpoint",
+            @"ppsm" : @"application/vnd.ms-powerpoint.slideshow.macroenabled.12",
+            @"ppsx" : @"application/vnd.openxmlformats-officedocument.presentationml.slideshow",
+            @"ppt" : @"application/vnd.ms-powerpoint",
+            @"pptm" : @"application/vnd.ms-powerpoint.presentation.macroenabled.12",
+            @"pptx" : @"application/vnd.openxmlformats-officedocument.presentationml.presentation",
+            @"pqa" : @"application/vnd.palm",
+            @"prc" : @"application/x-mobipocket-ebook",
+            @"pre" : @"application/vnd.lotus-freelance",
+            @"prf" : @"application/pics-rules",
+            @"ps" : @"application/postscript",
+            @"psb" : @"application/vnd.3gpp.pic-bw-small",
+            @"psd" : @"image/vnd.adobe.photoshop",
+            @"psf" : @"application/x-font-linux-psf",
+            @"pskcxml" : @"application/pskc+xml",
+            @"ptid" : @"application/vnd.pvi.ptid1",
+            @"pub" : @"application/x-mspublisher",
+            @"pvb" : @"application/vnd.3gpp.pic-bw-var",
+            @"pwn" : @"application/vnd.3m.post-it-notes",
+            @"pya" : @"audio/vnd.ms-playready.media.pya",
+            @"pyv" : @"video/vnd.ms-playready.media.pyv",
+            @"qam" : @"application/vnd.epson.quickanime",
+            @"qbo" : @"application/vnd.intu.qbo",
+            @"qfx" : @"application/vnd.intu.qfx",
+            @"qps" : @"application/vnd.publishare-delta-tree",
+            @"qt" : @"video/quicktime",
+            @"qwd" : @"application/vnd.quark.quarkxpress",
+            @"qwt" : @"application/vnd.quark.quarkxpress",
+            @"qxb" : @"application/vnd.quark.quarkxpress",
+            @"qxd" : @"application/vnd.quark.quarkxpress",
+            @"qxl" : @"application/vnd.quark.quarkxpress",
+            @"qxt" : @"application/vnd.quark.quarkxpress",
+            @"ra" : @"audio/x-pn-realaudio",
+            @"ram" : @"audio/x-pn-realaudio",
+            @"rar" : @"application/x-rar-compressed",
+            @"ras" : @"image/x-cmu-raster",
+            @"rcprofile" : @"application/vnd.ipunplugged.rcprofile",
+            @"rdf" : @"application/rdf+xml",
+            @"rdz" : @"application/vnd.data-vision.rdz",
+            @"rep" : @"application/vnd.businessobjects",
+            @"res" : @"application/x-dtbresource+xml",
+            @"rgb" : @"image/x-rgb",
+            @"rif" : @"application/reginfo+xml",
+            @"rip" : @"audio/vnd.rip",
+            @"ris" : @"application/x-research-info-systems",
+            @"rl" : @"application/resource-lists+xml",
+            @"rlc" : @"image/vnd.fujixerox.edmics-rlc",
+            @"rld" : @"application/resource-lists-diff+xml",
+            @"rm" : @"application/vnd.rn-realmedia",
+            @"rmi" : @"audio/midi",
+            @"rmp" : @"audio/x-pn-realaudio-plugin",
+            @"rms" : @"application/vnd.jcp.javame.midlet-rms",
+            @"rmvb" : @"application/vnd.rn-realmedia-vbr",
+            @"rnc" : @"application/relax-ng-compact-syntax",
+            @"roa" : @"application/rpki-roa",
+            @"roff" : @"text/troff",
+            @"rp9" : @"application/vnd.cloanto.rp9",
+            @"rpss" : @"application/vnd.nokia.radio-presets",
+            @"rpst" : @"application/vnd.nokia.radio-preset",
+            @"rq" : @"application/sparql-query",
+            @"rs" : @"application/rls-services+xml",
+            @"rsd" : @"application/rsd+xml",
+            @"rss" : @"application/rss+xml",
+            @"rtf" : @"application/rtf",
+            @"rtx" : @"text/richtext",
+            @"s" : @"text/x-asm",
+            @"s3m" : @"audio/s3m",
+            @"saf" : @"application/vnd.yamaha.smaf-audio",
+            @"sbml" : @"application/sbml+xml",
+            @"sc" : @"application/vnd.ibm.secure-container",
+            @"scd" : @"application/x-msschedule",
+            @"scm" : @"application/vnd.lotus-screencam",
+            @"scq" : @"application/scvp-cv-request",
+            @"scs" : @"application/scvp-cv-response",
+            @"scurl" : @"text/vnd.curl.scurl",
+            @"sda" : @"application/vnd.stardivision.draw",
+            @"sdc" : @"application/vnd.stardivision.calc",
+            @"sdd" : @"application/vnd.stardivision.impress",
+            @"sdkd" : @"application/vnd.solent.sdkm+xml",
+            @"sdkm" : @"application/vnd.solent.sdkm+xml",
+            @"sdp" : @"application/sdp",
+            @"sdw" : @"application/vnd.stardivision.writer",
+            @"see" : @"application/vnd.seemail",
+            @"seed" : @"application/vnd.fdsn.seed",
+            @"sema" : @"application/vnd.sema",
+            @"semd" : @"application/vnd.semd",
+            @"semf" : @"application/vnd.semf",
+            @"ser" : @"application/java-serialized-object",
+            @"setpay" : @"application/set-payment-initiation",
+            @"setreg" : @"application/set-registration-initiation",
+            @"sfd-hdstx" : @"application/vnd.hydrostatix.sof-data",
+            @"sfs" : @"application/vnd.spotfire.sfs",
+            @"sfv" : @"text/x-sfv",
+            @"sgi" : @"image/sgi",
+            @"sgl" : @"application/vnd.stardivision.writer-global",
+            @"sgm" : @"text/sgml",
+            @"sgml" : @"text/sgml",
+            @"sh" : @"application/x-sh",
+            @"shar" : @"application/x-shar",
+            @"shf" : @"application/shf+xml",
+            @"sid" : @"image/x-mrsid-image",
+            @"sig" : @"application/pgp-signature",
+            @"sil" : @"audio/silk",
+            @"silo" : @"model/mesh",
+            @"sis" : @"application/vnd.symbian.install",
+            @"sisx" : @"application/vnd.symbian.install",
+            @"sit" : @"application/x-stuffit",
+            @"sitx" : @"application/x-stuffitx",
+            @"skd" : @"application/vnd.koan",
+            @"skm" : @"application/vnd.koan",
+            @"skp" : @"application/vnd.koan",
+            @"skt" : @"application/vnd.koan",
+            @"sldm" : @"application/vnd.ms-powerpoint.slide.macroenabled.12",
+            @"sldx" : @"application/vnd.openxmlformats-officedocument.presentationml.slide",
+            @"slt" : @"application/vnd.epson.salt",
+            @"sm" : @"application/vnd.stepmania.stepchart",
+            @"smf" : @"application/vnd.stardivision.math",
+            @"smi" : @"application/smil+xml",
+            @"smil" : @"application/smil+xml",
+            @"smv" : @"video/x-smv",
+            @"smzip" : @"application/vnd.stepmania.package",
+            @"snd" : @"audio/basic",
+            @"snf" : @"application/x-font-snf",
+            @"so" : @"application/octet-stream",
+            @"spc" : @"application/x-pkcs7-certificates",
+            @"spf" : @"application/vnd.yamaha.smaf-phrase",
+            @"spl" : @"application/x-futuresplash",
+            @"spot" : @"text/vnd.in3d.spot",
+            @"spp" : @"application/scvp-vp-response",
+            @"spq" : @"application/scvp-vp-request",
+            @"spx" : @"audio/ogg",
+            @"sql" : @"application/x-sql",
+            @"src" : @"application/x-wais-source",
+            @"srt" : @"application/x-subrip",
+            @"sru" : @"application/sru+xml",
+            @"srx" : @"application/sparql-results+xml",
+            @"ssdl" : @"application/ssdl+xml",
+            @"sse" : @"application/vnd.kodak-descriptor",
+            @"ssf" : @"application/vnd.epson.ssf",
+            @"ssml" : @"application/ssml+xml",
+            @"st" : @"application/vnd.sailingtracker.track",
+            @"stc" : @"application/vnd.sun.xml.calc.template",
+            @"std" : @"application/vnd.sun.xml.draw.template",
+            @"stf" : @"application/vnd.wt.stf",
+            @"sti" : @"application/vnd.sun.xml.impress.template",
+            @"stk" : @"application/hyperstudio",
+            @"stl" : @"application/vnd.ms-pki.stl",
+            @"str" : @"application/vnd.pg.format",
+            @"stw" : @"application/vnd.sun.xml.writer.template",
+            @"sub" : @"text/vnd.dvb.subtitle",
+            @"sus" : @"application/vnd.sus-calendar",
+            @"susp" : @"application/vnd.sus-calendar",
+            @"sv4cpio" : @"application/x-sv4cpio",
+            @"sv4crc" : @"application/x-sv4crc",
+            @"svc" : @"application/vnd.dvb.service",
+            @"svd" : @"application/vnd.svd",
+            @"svg" : @"image/svg+xml",
+            @"svgz" : @"image/svg+xml",
+            @"swa" : @"application/x-director",
+            @"swf" : @"application/x-shockwave-flash",
+            @"swi" : @"application/vnd.aristanetworks.swi",
+            @"sxc" : @"application/vnd.sun.xml.calc",
+            @"sxd" : @"application/vnd.sun.xml.draw",
+            @"sxg" : @"application/vnd.sun.xml.writer.global",
+            @"sxi" : @"application/vnd.sun.xml.impress",
+            @"sxm" : @"application/vnd.sun.xml.math",
+            @"sxw" : @"application/vnd.sun.xml.writer",
+            @"t" : @"text/troff",
+            @"t3" : @"application/x-t3vm-image",
+            @"taglet" : @"application/vnd.mynfc",
+            @"tao" : @"application/vnd.tao.intent-module-archive",
+            @"tar" : @"application/x-tar",
+            @"tcap" : @"application/vnd.3gpp2.tcap",
+            @"tcl" : @"application/x-tcl",
+            @"teacher" : @"application/vnd.smart.teacher",
+            @"tei" : @"application/tei+xml",
+            @"teicorpus" : @"application/tei+xml",
+            @"tex" : @"application/x-tex",
+            @"texi" : @"application/x-texinfo",
+            @"texinfo" : @"application/x-texinfo",
+            @"text" : @"text/plain",
+            @"tfi" : @"application/thraud+xml",
+            @"tfm" : @"application/x-tex-tfm",
+            @"tga" : @"image/x-tga",
+            @"thmx" : @"application/vnd.ms-officetheme",
+            @"tif" : @"image/tiff",
+            @"tiff" : @"image/tiff",
+            @"tmo" : @"application/vnd.tmobile-livetv",
+            @"torrent" : @"application/x-bittorrent",
+            @"tpl" : @"application/vnd.groove-tool-template",
+            @"tpt" : @"application/vnd.trid.tpt",
+            @"tr" : @"text/troff",
+            @"tra" : @"application/vnd.trueapp",
+            @"trm" : @"application/x-msterminal",
+            @"tsd" : @"application/timestamped-data",
+            @"tsv" : @"text/tab-separated-values",
+            @"ttc" : @"application/x-font-ttf",
+            @"ttf" : @"application/x-font-ttf",
+            @"ttl" : @"text/turtle",
+            @"twd" : @"application/vnd.simtech-mindmapper",
+            @"twds" : @"application/vnd.simtech-mindmapper",
+            @"txd" : @"application/vnd.genomatix.tuxedo",
+            @"txf" : @"application/vnd.mobius.txf",
+            @"txt" : @"text/plain",
+            @"u32" : @"application/x-authorware-bin",
+            @"udeb" : @"application/x-debian-package",
+            @"ufd" : @"application/vnd.ufdl",
+            @"ufdl" : @"application/vnd.ufdl",
+            @"ulx" : @"application/x-glulx",
+            @"umj" : @"application/vnd.umajin",
+            @"unityweb" : @"application/vnd.unity",
+            @"uoml" : @"application/vnd.uoml+xml",
+            @"uri" : @"text/uri-list",
+            @"uris" : @"text/uri-list",
+            @"urls" : @"text/uri-list",
+            @"ustar" : @"application/x-ustar",
+            @"utz" : @"application/vnd.uiq.theme",
+            @"uu" : @"text/x-uuencode",
+            @"uva" : @"audio/vnd.dece.audio",
+            @"uvd" : @"application/vnd.dece.data",
+            @"uvf" : @"application/vnd.dece.data",
+            @"uvg" : @"image/vnd.dece.graphic",
+            @"uvh" : @"video/vnd.dece.hd",
+            @"uvi" : @"image/vnd.dece.graphic",
+            @"uvm" : @"video/vnd.dece.mobile",
+            @"uvp" : @"video/vnd.dece.pd",
+            @"uvs" : @"video/vnd.dece.sd",
+            @"uvt" : @"application/vnd.dece.ttml+xml",
+            @"uvu" : @"video/vnd.uvvu.mp4",
+            @"uvv" : @"video/vnd.dece.video",
+            @"uvva" : @"audio/vnd.dece.audio",
+            @"uvvd" : @"application/vnd.dece.data",
+            @"uvvf" : @"application/vnd.dece.data",
+            @"uvvg" : @"image/vnd.dece.graphic",
+            @"uvvh" : @"video/vnd.dece.hd",
+            @"uvvi" : @"image/vnd.dece.graphic",
+            @"uvvm" : @"video/vnd.dece.mobile",
+            @"uvvp" : @"video/vnd.dece.pd",
+            @"uvvs" : @"video/vnd.dece.sd",
+            @"uvvt" : @"application/vnd.dece.ttml+xml",
+            @"uvvu" : @"video/vnd.uvvu.mp4",
+            @"uvvv" : @"video/vnd.dece.video",
+            @"uvvx" : @"application/vnd.dece.unspecified",
+            @"uvvz" : @"application/vnd.dece.zip",
+            @"uvx" : @"application/vnd.dece.unspecified",
+            @"uvz" : @"application/vnd.dece.zip",
+            @"vcard" : @"text/vcard",
+            @"vcd" : @"application/x-cdlink",
+            @"vcf" : @"text/x-vcard",
+            @"vcg" : @"application/vnd.groove-vcard",
+            @"vcs" : @"text/x-vcalendar",
+            @"vcx" : @"application/vnd.vcx",
+            @"vis" : @"application/vnd.visionary",
+            @"viv" : @"video/vnd.vivo",
+            @"vob" : @"video/x-ms-vob",
+            @"vor" : @"application/vnd.stardivision.writer",
+            @"vox" : @"application/x-authorware-bin",
+            @"vrml" : @"model/vrml",
+            @"vsd" : @"application/vnd.visio",
+            @"vsf" : @"application/vnd.vsf",
+            @"vss" : @"application/vnd.visio",
+            @"vst" : @"application/vnd.visio",
+            @"vsw" : @"application/vnd.visio",
+            @"vtu" : @"model/vnd.vtu",
+            @"vxml" : @"application/voicexml+xml",
+            @"w3d" : @"application/x-director",
+            @"wad" : @"application/x-doom",
+            @"wav" : @"audio/x-wav",
+            @"wax" : @"audio/x-ms-wax",
+            @"wbmp" : @"image/vnd.wap.wbmp",
+            @"wbs" : @"application/vnd.criticaltools.wbs+xml",
+            @"wbxml" : @"application/vnd.wap.wbxml",
+            @"wcm" : @"application/vnd.ms-works",
+            @"wdb" : @"application/vnd.ms-works",
+            @"wdp" : @"image/vnd.ms-photo",
+            @"weba" : @"audio/webm",
+            @"webm" : @"video/webm",
+            @"webp" : @"image/webp",
+            @"wg" : @"application/vnd.pmi.widget",
+            @"wgt" : @"application/widget",
+            @"wks" : @"application/vnd.ms-works",
+            @"wm" : @"video/x-ms-wm",
+            @"wma" : @"audio/x-ms-wma",
+            @"wmd" : @"application/x-ms-wmd",
+            @"wmf" : @"application/x-msmetafile",
+            @"wml" : @"text/vnd.wap.wml",
+            @"wmlc" : @"application/vnd.wap.wmlc",
+            @"wmls" : @"text/vnd.wap.wmlscript",
+            @"wmlsc" : @"application/vnd.wap.wmlscriptc",
+            @"wmv" : @"video/x-ms-wmv",
+            @"wmx" : @"video/x-ms-wmx",
+            @"wmz" : @"application/x-msmetafile",
+            @"woff" : @"application/font-woff",
+            @"wpd" : @"application/vnd.wordperfect",
+            @"wpl" : @"application/vnd.ms-wpl",
+            @"wps" : @"application/vnd.ms-works",
+            @"wqd" : @"application/vnd.wqd",
+            @"wri" : @"application/x-mswrite",
+            @"wrl" : @"model/vrml",
+            @"wsdl" : @"application/wsdl+xml",
+            @"wspolicy" : @"application/wspolicy+xml",
+            @"wtb" : @"application/vnd.webturbo",
+            @"wvx" : @"video/x-ms-wvx",
+            @"x32" : @"application/x-authorware-bin",
+            @"x3d" : @"model/x3d+xml",
+            @"x3db" : @"model/x3d+binary",
+            @"x3dbz" : @"model/x3d+binary",
+            @"x3dv" : @"model/x3d+vrml",
+            @"x3dvz" : @"model/x3d+vrml",
+            @"x3dz" : @"model/x3d+xml",
+            @"xaml" : @"application/xaml+xml",
+            @"xap" : @"application/x-silverlight-app",
+            @"xar" : @"application/vnd.xara",
+            @"xbap" : @"application/x-ms-xbap",
+            @"xbd" : @"application/vnd.fujixerox.docuworks.binder",
+            @"xbm" : @"image/x-xbitmap",
+            @"xdf" : @"application/xcap-diff+xml",
+            @"xdm" : @"application/vnd.syncml.dm+xml",
+            @"xdp" : @"application/vnd.adobe.xdp+xml",
+            @"xdssc" : @"application/dssc+xml",
+            @"xdw" : @"application/vnd.fujixerox.docuworks",
+            @"xenc" : @"application/xenc+xml",
+            @"xer" : @"application/patch-ops-error+xml",
+            @"xfdf" : @"application/vnd.adobe.xfdf",
+            @"xfdl" : @"application/vnd.xfdl",
+            @"xht" : @"application/xhtml+xml",
+            @"xhtml" : @"application/xhtml+xml",
+            @"xhvml" : @"application/xv+xml",
+            @"xif" : @"image/vnd.xiff",
+            @"xla" : @"application/vnd.ms-excel",
+            @"xlam" : @"application/vnd.ms-excel.addin.macroenabled.12",
+            @"xlc" : @"application/vnd.ms-excel",
+            @"xlf" : @"application/x-xliff+xml",
+            @"xlm" : @"application/vnd.ms-excel",
+            @"xls" : @"application/vnd.ms-excel",
+            @"xlsb" : @"application/vnd.ms-excel.sheet.binary.macroenabled.12",
+            @"xlsm" : @"application/vnd.ms-excel.sheet.macroenabled.12",
+            @"xlsx" : @"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
+            @"xlt" : @"application/vnd.ms-excel",
+            @"xltm" : @"application/vnd.ms-excel.template.macroenabled.12",
+            @"xltx" : @"application/vnd.openxmlformats-officedocument.spreadsheetml.template",
+            @"xlw" : @"application/vnd.ms-excel",
+            @"xm" : @"audio/xm",
+            @"xml" : @"application/xml",
+            @"xo" : @"application/vnd.olpc-sugar",
+            @"xop" : @"application/xop+xml",
+            @"xpi" : @"application/x-xpinstall",
+            @"xpl" : @"application/xproc+xml",
+            @"xpm" : @"image/x-xpixmap",
+            @"xpr" : @"application/vnd.is-xpr",
+            @"xps" : @"application/vnd.ms-xpsdocument",
+            @"xpw" : @"application/vnd.intercon.formnet",
+            @"xpx" : @"application/vnd.intercon.formnet",
+            @"xsl" : @"application/xml",
+            @"xslt" : @"application/xslt+xml",
+            @"xsm" : @"application/vnd.syncml+xml",
+            @"xspf" : @"application/xspf+xml",
+            @"xul" : @"application/vnd.mozilla.xul+xml",
+            @"xvm" : @"application/xv+xml",
+            @"xvml" : @"application/xv+xml",
+            @"xwd" : @"image/x-xwindowdump",
+            @"xyz" : @"chemical/x-xyz",
+            @"xz" : @"application/x-xz",
+            @"yang" : @"application/yang",
+            @"yin" : @"application/yin+xml",
+            @"z1" : @"application/x-zmachine",
+            @"z2" : @"application/x-zmachine",
+            @"z3" : @"application/x-zmachine",
+            @"z4" : @"application/x-zmachine",
+            @"z5" : @"application/x-zmachine",
+            @"z6" : @"application/x-zmachine",
+            @"z7" : @"application/x-zmachine",
+            @"z8" : @"application/x-zmachine",
+            @"zaz" : @"application/vnd.zzazz.deck+xml",
+            @"zip" : @"application/zip",
+            @"zir" : @"application/vnd.zul",
+            @"zirz" : @"application/vnd.zul",
+            @"zmm" : @"application/vnd.handheld-entertainment+xml",
+        };
+    });
+    return result;
+}
+
 + (nullable NSString *)fileExtensionForMIMETypeViaLookup:(NSString *)mimeType
 {
     return [[self genericMIMETypesToExtensionTypes] objectForKey:mimeType];
@@ -1553,11 +2568,16 @@ NSString *const OWSMimeTypeUnknownForTests = @"unknown/mimetype";
 
 + (nullable NSString *)fileExtensionForMIMEType:(NSString *)mimeType
 {
-    // Try to deduce the file extension by converting to a UTI type.
-    NSString *_Nullable fileExtension = [self fileExtensionForMIMETypeViaUTIType:mimeType];
+    // Try to deduce the file extension by using a lookup table.
+    //
+    // This should be more accurate than deducing the file extension by
+    // converting to a UTI type.  For example, .m4a files will have a
+    // UTI type of kUTTypeMPEG4Audio which incorrectly yields the file
+    // extension .mp4 instead of .m4a.
+    NSString *_Nullable fileExtension = [self fileExtensionForMIMETypeViaLookup:mimeType];
     if (!fileExtension) {
-        // Try to deduce the file extension by using a lookup table..
-        fileExtension = [self fileExtensionForMIMETypeViaLookup:mimeType];
+        // Try to deduce the file extension by converting to a UTI type.
+        fileExtension = [self fileExtensionForMIMETypeViaUTIType:mimeType];
     }
     return fileExtension;
 }