@@ -297,12 +297,14 @@
 		@throw [OFNotOpenException exceptionWithObject: self];
 
 	if (_atEndOfStream)
 		return 0;
 
-	if (sizeof(length) >= sizeof(uint64_t) && length > UINT64_MAX)
+#if SIZE_MAX >= UINT64_MAX
+	if (length > UINT64_MAX)
 		@throw [OFOutOfRangeException exception];
+#endif
 
 	if ((uint64_t)length > _toRead)
 		length = (size_t)_toRead;
 
 	ret = [_stream readIntoBuffer: buffer
@@ -376,11 +378,11 @@
 
 		size = [_entry size];
 
 		if (size % 512 != 0)
 			[_stream readIntoBuffer: buffer
-				    exactLength: 512 - (size % 512)];
+				    exactLength: (size_t)(512 - (size % 512))];
 	}
 }
 @end
 
 @implementation OFTarArchive_FileWriteStream