diff --git a/Signal/src/contact/OWSContactsManager.m b/Signal/src/contact/OWSContactsManager.m
index 176bc3adb..350e0eeb6 100644
--- a/Signal/src/contact/OWSContactsManager.m
+++ b/Signal/src/contact/OWSContactsManager.m
@@ -38,7 +38,7 @@ typedef BOOL (^ContactSearchBlock)(id, NSUInteger, BOOL *);
 }
 
 - (void)doAfterEnvironmentInitSetup {
-    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(_iOS_9)) {
+    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(9, 0)) {
         self.contactStore = [[CNContactStore alloc] init];
         [self.contactStore requestAccessForEntityType:CNEntityTypeContacts
                                     completionHandler:^(BOOL granted, NSError *_Nullable error) {
diff --git a/Signal/src/environment/iOSVersions.h b/Signal/src/environment/iOSVersions.h
index a8ebb772f..d1f60d207 100644
--- a/Signal/src/environment/iOSVersions.h
+++ b/Signal/src/environment/iOSVersions.h
@@ -9,94 +9,6 @@
 #import <Foundation/Foundation.h>
 #include <Availability.h>
 
-// Source: https://github.com/carlj/CJAMacros/blob/master/CJAMacros/CJAMacros.h
+#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(major, minor) \
+    ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion){.majorVersion = major, .minorVersion = minor, .patchVersion = 0}])
 
-/**
- Runtime check for the current version Nummer.
- checks ( CURRENT_VERSION_NUMBR == GIVEN_VERSION_NUMBER)
- @_gVersion - the given Version Number. aka (_iOS_7_0 or NSFoundationVersionNumber_iOS_7_0 and so on)
- */
-#define SYSTEM_VERSION_EQUAL_TO(_gVersion)                  ( floor(NSFoundationVersionNumber) == _gVersion )
-
-/**
- Runtime check for the current version Nummer.
- checks CURRENT_VERSION_NUMBER > GIVEN_VERSION_NUMBER
- @_gVersion - the given Version Number. aka (_iOS_7_0 or NSFoundationVersionNumber_iOS_7_0 and so on)
- */
-#define SYSTEM_VERSION_GREATER_THAN(_gVersion)              ( floor(NSFoundationVersionNumber) >  _gVersion )
-
-/**
- Runtime check for the current version Nummer.
- checks CURRENT_VERSION_NUMBER >= GIVEN_VERSION_NUMBER
- @_gVersion - the given Version Number. aka (_iOS_7_0 or NSFoundationVersionNumber_iOS_7_0 and so on)
- */
-#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(_gVersion)  ( floor(NSFoundationVersionNumber) >= _gVersion )
-
-
-/**
- Runtime check for the current version Nummer.
- checks CURRENT_VERSION_NUMBER < GIVEN_VERSION_NUMBER
- @_gVersion - the given Version Number. aka (_iOS_7_0 or NSFoundationVersionNumber_iOS_7_0 and so on)
- */
-#define SYSTEM_VERSION_LESS_THAN(_gVersion)                 ( floor(NSFoundationVersionNumber) <  _gVersion )
-
-
-/**
- Runtime check for the current version Nummer.
- checks CURRENT_VERSION_NUMBER <= GIVEN_VERSION_NUMBER
- @_gVersion - the given Version Number. aka (_iOS_7_0 or NSFoundationVersionNumber_iOS_7_0 and so on)
- */
-#define SYSTEM_VERSION_LESS_THAN_OR_EQUAL_TO(_gVersion)     ( floor(NSFoundationVersionNumber) <= _gVersion )
-
-
-//If the symbol for iOS 7 isnt defined, define it.
-#ifndef NSFoundationVersionNumber_iOS_7_0
-#define NSFoundationVersionNumber_iOS_7_0 1047.00 //extracted from iOS 7 Header
-#endif
-
-#ifdef NSFoundationVersionNumber_iOS_7_0
-#define _iOS_7_0 NSFoundationVersionNumber_iOS_7_0
-#endif
-
-//If the symbol for iOS 7.1 isnt defined, define it.
-#ifndef NSFoundationVersionNumber_iOS_7_1
-#define NSFoundationVersionNumber_iOS_7_1 1047.25 //extracted from iOS 8 Header
-#endif
-
-#ifdef NSFoundationVersionNumber_iOS_7_1
-#define _iOS_7_1 NSFoundationVersionNumber_iOS_7_1
-#endif
-
-//If the symbol for iOS 8 isnt defined, define it.
-#ifndef NSFoundationVersionNumber_iOS_8_0
-#define NSFoundationVersionNumber_iOS_8_0 1134.10 //extracted with NSLog(@"%f", NSFoundationVersionNumber)
-#endif
-
-#ifdef NSFoundationVersionNumber_iOS_8_0
-#define _iOS_8_0 NSFoundationVersionNumber_iOS_8_0
-#endif
-
-#ifndef NSFoundationVersionNumber_iOS_8_0_2
-#define NSFoundationVersionNumber_iOS_8_0_2 1140.110000 //extracted with NSLog(@"%f", NSFoundationVersionNumber)
-#endif
-
-#ifdef NSFoundationVersionNumber_iOS_8_0_2
-#define _iOS_8_0_2 NSFoundationVersionNumber_iOS_8_0_2
-#endif
-
-
-#ifndef NSFoundationVersionNumber_iOS_8_2_0
-#define NSFoundationVersionNumber_iOS_8_2_0 1142 //extracted with NSLog(@"%f", NSFoundationVersionNumber)
-#endif
-
-#ifdef NSFoundationVersionNumber_iOS_8_2_0
-#define _iOS_8_2_0 NSFoundationVersionNumber_iOS_8_2_0
-#endif
-
-#ifndef NSFoundationVersionNumber_iOS_9
-#define NSFoundationVersionNumber_iOS_9 1231 //extracted with NSLog(@"%f", NSFoundationVersionNumber)
-#endif
-
-#ifdef NSFoundationVersionNumber_iOS_9
-#define _iOS_9 NSFoundationVersionNumber_iOS_9
-#endif
diff --git a/Signal/src/network/PushManager.m b/Signal/src/network/PushManager.m
index e0701db89..3bc4a1665 100644
--- a/Signal/src/network/PushManager.m
+++ b/Signal/src/network/PushManager.m
@@ -394,7 +394,7 @@
 }
 
 - (BOOL)supportsVOIPPush {
-    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(_iOS_8_2_0)) {
+    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(8, 2)) {
         return YES;
     } else {
         return NO;
@@ -449,7 +449,7 @@
     action_reply.title                            = NSLocalizedString(@"PUSH_MANAGER_REPLY", @"");
     action_reply.destructive                      = NO;
     action_reply.authenticationRequired           = NO; // Since YES is broken in iOS 9 GM
-    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(_iOS_9)) {
+    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(9, 0)) {
         action_reply.behavior       = UIUserNotificationActionBehaviorTextInput;
         action_reply.activationMode = UIUserNotificationActivationModeBackground;
     } else {
diff --git a/Signal/src/util/UIFont+OWS.m b/Signal/src/util/UIFont+OWS.m
index ea1b68526..613feddfd 100644
--- a/Signal/src/util/UIFont+OWS.m
+++ b/Signal/src/util/UIFont+OWS.m
@@ -12,19 +12,35 @@
 @implementation UIFont (OWS)
 
 + (UIFont *)ows_thinFontWithSize:(CGFloat)size {
-    return [UIFont systemFontOfSize:size weight:UIFontWeightThin];
+    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(8, 2)) {
+        return [UIFont systemFontOfSize:size weight:UIFontWeightThin];
+    } else {
+        return [UIFont fontWithName:@"HelveticaNeue-Thin" size:size];
+    }
 }
 
 + (UIFont *)ows_lightFontWithSize:(CGFloat)size {
-    return [UIFont systemFontOfSize:size weight:UIFontWeightLight];
+    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(8, 2)) {
+        return [UIFont systemFontOfSize:size weight:UIFontWeightLight];
+    } else {
+        return [UIFont fontWithName:@"HelveticaNeue-Light" size:size];
+    }
 }
 
 + (UIFont *)ows_regularFontWithSize:(CGFloat)size {
-    return [UIFont systemFontOfSize:size weight:UIFontWeightRegular];
+    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(8, 2)) {
+        return [UIFont systemFontOfSize:size weight:UIFontWeightRegular];
+    } else {
+        return [UIFont fontWithName:@"HelveticaNeue" size:size];
+    }
 }
 
 + (UIFont *)ows_mediumFontWithSize:(CGFloat)size {
-    return [UIFont systemFontOfSize:size weight:UIFontWeightMedium];
+    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(8, 2)) {
+        return [UIFont systemFontOfSize:size weight:UIFontWeightMedium];
+    } else {
+        return [UIFont fontWithName:@"HelveticaNeue-Medium" size:size];
+    }
 }
 
 + (UIFont *)ows_boldFontWithSize:(CGFloat)size {
@@ -43,7 +59,7 @@
 }
 
 + (UIFont *)ows_dynamicTypeTitle2Font {
-    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(_iOS_9)) {
+    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(9, 0)) {
         return [UIFont preferredFontForTextStyle:UIFontTextStyleTitle2];
     } else {
         // Dynamic title font for ios8 defaults to bold 12.0 pt, whereas ios9+ it's 22.0pt regular weight.