@@ -248,11 +248,15 @@
 {
 	if (string == nil)
 		@throw [OFInvalidArgumentException newWithClass: isa
 						       selector: _cmd];
 
-	[self appendCString: [string cString]];
+	[self appendCStringWithoutUTF8Checking: [string cString]
+					length: [string cStringLength]];
+
+	if (string->s->isUTF8)
+		s->isUTF8 = YES;
 }
 
 - (void)appendFormat: (OFConstantString*)format, ...
 {
 	va_list arguments;