@@ -268,17 +268,18 @@
 	      format: (OFString*)format
 {
 	self = [super init];
 
 	@try {
+		const char *UTF8String = [string UTF8String];
 		struct tm tm = { 0 };
 		int16_t tz = 0;
 
 		tm.tm_isdst = -1;
 
-		if (of_strptime([string UTF8String], [format UTF8String],
-		    &tm, &tz) == NULL)
+		if (of_strptime(UTF8String, [format UTF8String],
+		    &tm, &tz) != UTF8String + [string UTF8StringLength])
 			@throw [OFInvalidFormatException exception];
 
 		_seconds = tmAndTzToTime(&tm, &tz);
 	} @catch (id e) {
 		[self release];
@@ -292,10 +293,11 @@
 		   format: (OFString*)format
 {
 	self = [super init];
 
 	@try {
+		const char *UTF8String = [string UTF8String];
 		struct tm tm = { 0 };
 		/*
 		 * of_strptime() can never set this to INT16_MAX, no matter
 		 * what is passed to it, so this is a safe way to figure out if
 		 * the date contains a time zone.
@@ -302,12 +304,12 @@
 		 */
 		int16_t tz = INT16_MAX;
 
 		tm.tm_isdst = -1;
 
-		if (of_strptime([string UTF8String], [format UTF8String],
-		    &tm, &tz) == NULL)
+		if (of_strptime(UTF8String, [format UTF8String],
+		    &tm, &tz) != UTF8String + [string UTF8StringLength])
 			@throw [OFInvalidFormatException exception];
 
 		if (tz == INT16_MAX) {
 #ifndef OF_WINDOWS
 			if ((_seconds = mktime(&tm)) == -1)