diff --git a/MTDates/NSDate+MTDates.m b/MTDates/NSDate+MTDates.m
index 0ad5f2a..d0016e0 100644
--- a/MTDates/NSDate+MTDates.m
+++ b/MTDates/NSDate+MTDates.m
@@ -392,6 +392,7 @@ - (NSInteger)mt_weekdayOfWeek
     NSInteger weekdayOfWeek = [[NSDate mt_calendar] ordinalityOfUnit:NSCalendarUnitWeekday
                                                                inUnit:NSCalendarUnitWeekOfYear
                                                               forDate:self];
+	weekdayOfWeek += [[NSDate mt_calendar] firstWeekday] - 1;
 	[[NSDate sharedRecursiveLock] unlock];
     return weekdayOfWeek;
 }
@@ -693,7 +694,7 @@ - (NSDate *)mt_startOfCurrentWeek
 {
 	[[NSDate sharedRecursiveLock] lock];
     NSInteger weekday = [self mt_weekdayOfWeek];
-    NSDate *date = [self mt_dateDaysAfter:-(weekday - 1)];
+    NSDate *date = [self mt_dateDaysAfter:-(weekday - [[NSDate mt_calendar] firstWeekday])];
     NSDate *startOfCurrentWeek = [NSDate mt_dateFromYear:[date mt_year]
                                                    month:[date mt_monthOfYear]
                                                      day:[date mt_dayOfMonth]
diff --git a/MTDatesTests/MTDatesTests.m b/MTDatesTests/MTDatesTests.m
index 6d79690..aebc2a8 100644
--- a/MTDatesTests/MTDatesTests.m
+++ b/MTDatesTests/MTDatesTests.m
@@ -1065,6 +1065,62 @@ - (void)test_firstDayOfWeek
     [NSDate mt_setFirstDayOfWeek:1];
 }
 
+- (void)test_firstDayOfWeek2
+{
+    NSDate *date = [_formatter dateFromString:@"07/11/1986 09:23am"];
+    
+    [NSDate mt_setFirstDayOfWeek:1];
+    XCTAssertEqualObjects([NSDate mt_dateFromYear:[date mt_year]
+                                            week:[date mt_weekOfYear]
+                                         weekday:[date mt_weekdayOfWeek]
+                                            hour:[date mt_hourOfDay]
+                                          minute:[date mt_minuteOfHour]], date);
+    
+    [NSDate mt_setFirstDayOfWeek:2];
+    XCTAssertEqualObjects([NSDate mt_dateFromYear:[date mt_year]
+                                            week:[date mt_weekOfYear]
+                                         weekday:[date mt_weekdayOfWeek]
+                                            hour:[date mt_hourOfDay]
+                                          minute:[date mt_minuteOfHour]], date);
+    
+    [NSDate mt_setFirstDayOfWeek:3];
+    XCTAssertEqualObjects([NSDate mt_dateFromYear:[date mt_year]
+                                            week:[date mt_weekOfYear]
+                                         weekday:[date mt_weekdayOfWeek]
+                                            hour:[date mt_hourOfDay]
+                                          minute:[date mt_minuteOfHour]], date);
+    
+    [NSDate mt_setFirstDayOfWeek:4];
+    XCTAssertEqualObjects([NSDate mt_dateFromYear:[date mt_year]
+                                            week:[date mt_weekOfYear]
+                                         weekday:[date mt_weekdayOfWeek]
+                                            hour:[date mt_hourOfDay]
+                                          minute:[date mt_minuteOfHour]], date);
+    
+    [NSDate mt_setFirstDayOfWeek:5];
+    XCTAssertEqualObjects([NSDate mt_dateFromYear:[date mt_year]
+                                            week:[date mt_weekOfYear]
+                                         weekday:[date mt_weekdayOfWeek]
+                                            hour:[date mt_hourOfDay]
+                                          minute:[date mt_minuteOfHour]], date);
+    
+    [NSDate mt_setFirstDayOfWeek:6];
+    XCTAssertEqualObjects([NSDate mt_dateFromYear:[date mt_year]
+                                            week:[date mt_weekOfYear]
+                                         weekday:[date mt_weekdayOfWeek]
+                                            hour:[date mt_hourOfDay]
+                                          minute:[date mt_minuteOfHour]], date);
+    
+    [NSDate mt_setFirstDayOfWeek:7];
+    XCTAssertEqualObjects([NSDate mt_dateFromYear:[date mt_year]
+                                            week:[date mt_weekOfYear]
+                                         weekday:[date mt_weekdayOfWeek]
+                                            hour:[date mt_hourOfDay]
+                                          minute:[date mt_minuteOfHour]], date);
+    
+    [NSDate mt_setFirstDayOfWeek:1];
+}
+
 - (void)test_firstWeekOfYear
 {
     NSDate *date = nil;