diff --git a/Signal/src/util/DateUtil.m b/Signal/src/util/DateUtil.m
index d22255f41..168728be2 100644
--- a/Signal/src/util/DateUtil.m
+++ b/Signal/src/util/DateUtil.m
@@ -78,11 +78,8 @@ static NSString *const DATE_FORMAT_WEEKDAY = @"EEEE";
 
 + (BOOL)dateIsOlderThanToday:(NSDate *)date now:(NSDate *)now
 {
-    NSCalendar *calendar = [NSCalendar currentCalendar];
-
-    NSUInteger dateDayOfEra = [calendar ordinalityOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitEra forDate:date];
-    NSUInteger nowDayOfEra = [calendar ordinalityOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitEra forDate:now];
-    return dateDayOfEra < nowDayOfEra;
+    NSInteger dayDifference = [self daysFromFirstDate:date toSecondDate:now];
+    return dayDifference > 0;
 }
 
 + (BOOL)dateIsOlderThanOneWeek:(NSDate *)date
@@ -92,11 +89,8 @@ static NSString *const DATE_FORMAT_WEEKDAY = @"EEEE";
 
 + (BOOL)dateIsOlderThanOneWeek:(NSDate *)date now:(NSDate *)now
 {
-    NSCalendar *calendar = [NSCalendar currentCalendar];
-
-    NSUInteger dateDayOfEra = [calendar ordinalityOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitEra forDate:date];
-    NSUInteger nowDayOfEra = [calendar ordinalityOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitEra forDate:now];
-    return dateDayOfEra < (nowDayOfEra - 6);
+    NSInteger dayDifference = [self daysFromFirstDate:date toSecondDate:now];
+    return dayDifference > 6;
 }
 
 + (BOOL)dateIsToday:(NSDate *)date
@@ -106,9 +100,8 @@ static NSString *const DATE_FORMAT_WEEKDAY = @"EEEE";
 
 + (BOOL)dateIsToday:(NSDate *)date now:(NSDate *)now
 {
-    NSCalendar *calendar = [NSCalendar currentCalendar];
-    return ([calendar ordinalityOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitEra forDate:date] ==
-        [calendar ordinalityOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitEra forDate:now]);
+    NSInteger dayDifference = [self daysFromFirstDate:date toSecondDate:now];
+    return dayDifference == 0;
 }
 
 + (BOOL)dateIsThisYear:(NSDate *)date
@@ -129,10 +122,27 @@ static NSString *const DATE_FORMAT_WEEKDAY = @"EEEE";
 }
 
 + (BOOL)dateIsYesterday:(NSDate *)date now:(NSDate *)now
+{
+    NSInteger dayDifference = [self daysFromFirstDate:date toSecondDate:now];
+    return dayDifference == 1;
+}
+
+// Returns the difference in days, ignoring hours, minutes, seconds.
+// If both dates are the same date, returns 0.
+// If firstDate is a day before secondDate, returns 1.
+//
+// Note: Assumes both dates use the "current" calendar.
++ (NSInteger)daysFromFirstDate:(NSDate *)firstDate toSecondDate:(NSDate *)secondDate
 {
     NSCalendar *calendar = [NSCalendar currentCalendar];
-    return ([calendar ordinalityOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitEra forDate:date] ==
-        [calendar ordinalityOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitEra forDate:now] - 1);
+    NSCalendarUnit units = NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
+    NSDateComponents *comp1 = [calendar components:units fromDate:firstDate];
+    NSDateComponents *comp2 = [calendar components:units fromDate:secondDate];
+    [comp1 setHour:12];
+    [comp2 setHour:12];
+    NSDate *date1 = [calendar dateFromComponents:comp1];
+    NSDate *date2 = [calendar dateFromComponents:comp2];
+    return [[calendar components:NSCalendarUnitDay fromDate:date1 toDate:date2 options:0] day];
 }
 
 + (NSString *)formatPastTimestampRelativeToNow:(uint64_t)pastTimestamp isRTL:(BOOL)isRTL
diff --git a/Signal/test/util/UtilTest.m b/Signal/test/util/UtilTest.m
index 4091725f9..308d3ae39 100644
--- a/Signal/test/util/UtilTest.m
+++ b/Signal/test/util/UtilTest.m
@@ -214,6 +214,58 @@
     XCTAssertFalse([DateUtil dateIsThisYear:twoYearsAhead now:now]);
 }
 
+- (NSDate *)dateWithYear:(NSInteger)year
+                   month:(NSInteger)month
+                     day:(NSInteger)day
+                    hour:(NSInteger)hour
+                  minute:(NSInteger)minute
+{
+    NSDateComponents *components = [NSDateComponents new];
+    components.year = year;
+    components.month = month;
+    components.day = day;
+    components.hour = hour;
+    components.minute = minute;
+    return [[NSCalendar currentCalendar] dateFromComponents:components];
+}
+
+- (void)testDateComparators_timezoneVMidnight
+{
+    NSDateFormatter *formatter = [NSDateFormatter new];
+    formatter.dateStyle = NSDateFormatterLongStyle;
+    formatter.timeStyle = NSDateFormatterLongStyle;
+
+    NSDate *yesterdayBeforeMidnight = [self dateWithYear:2015 month:8 day:10 hour:23 minute:55];
+    NSLog(@"yesterdayBeforeMidnight: %@", [formatter stringFromDate:yesterdayBeforeMidnight]);
+
+    NSDate *todayAfterMidnight = [self dateWithYear:2015 month:8 day:11 hour:0 minute:5];
+    NSLog(@"todayAfterMidnight: %@", [formatter stringFromDate:todayAfterMidnight]);
+
+    NSDate *todayNoon = [self dateWithYear:2015 month:8 day:11 hour:12 minute:0];
+    NSLog(@"todayNoon: %@", [formatter stringFromDate:todayNoon]);
+
+    // Before Midnight, after Midnight.
+    XCTAssertFalse([DateUtil dateIsToday:yesterdayBeforeMidnight now:todayAfterMidnight]);
+    XCTAssertTrue([DateUtil dateIsYesterday:yesterdayBeforeMidnight now:todayAfterMidnight]);
+    XCTAssertTrue([DateUtil dateIsOlderThanToday:yesterdayBeforeMidnight now:todayAfterMidnight]);
+    XCTAssertFalse([DateUtil dateIsOlderThanOneWeek:yesterdayBeforeMidnight now:todayAfterMidnight]);
+    XCTAssertTrue([DateUtil dateIsThisYear:yesterdayBeforeMidnight now:todayAfterMidnight]);
+
+    // Before Midnight, noon.
+    XCTAssertFalse([DateUtil dateIsToday:yesterdayBeforeMidnight now:todayNoon]);
+    XCTAssertTrue([DateUtil dateIsYesterday:yesterdayBeforeMidnight now:todayNoon]);
+    XCTAssertTrue([DateUtil dateIsOlderThanToday:yesterdayBeforeMidnight now:todayNoon]);
+    XCTAssertFalse([DateUtil dateIsOlderThanOneWeek:yesterdayBeforeMidnight now:todayNoon]);
+    XCTAssertTrue([DateUtil dateIsThisYear:yesterdayBeforeMidnight now:todayNoon]);
+
+    // After Midnight, noon.
+    XCTAssertTrue([DateUtil dateIsToday:todayAfterMidnight now:todayNoon]);
+    XCTAssertFalse([DateUtil dateIsYesterday:todayAfterMidnight now:todayNoon]);
+    XCTAssertFalse([DateUtil dateIsOlderThanToday:todayAfterMidnight now:todayNoon]);
+    XCTAssertFalse([DateUtil dateIsOlderThanOneWeek:todayAfterMidnight now:todayNoon]);
+    XCTAssertTrue([DateUtil dateIsThisYear:todayAfterMidnight now:todayNoon]);
+}
+
 - (void)testObjectComparison
 {
     XCTAssertTrue([NSObject isNullableObject:nil equalTo:nil]);