@@ -105,11 +105,11 @@
 		_bitIndex = 8;
 
 		_distanceBits = distanceBits;
 		_dictionaryBits = dictionaryBits;
 
-		_slidingWindowMask = (1 << dictionaryBits) - 1;
+		_slidingWindowMask = (1u << dictionaryBits) - 1;
 		_slidingWindow = [self allocMemoryWithSize:
 		    _slidingWindowMask + 1];
 		memset(_slidingWindow, ' ', _slidingWindowMask + 1);
 	} @catch (id e) {
 		[self release];
@@ -454,11 +454,11 @@
 		goto start;
 	case STATE_BLOCK_DIST_LENGTH_EXTRA:
 		if OF_UNLIKELY (!tryReadBits(self, &bits, _distance - 1))
 			return bytesWritten;
 
-		_distance = bits + (1 << (_distance - 1));
+		_distance = bits + (1u << (_distance - 1));
 
 		_state = STATE_BLOCK_LEN_DIST_PAIR;
 		goto start;
 	case STATE_BLOCK_LEN_DIST_PAIR:
 		for (uint_fast16_t i = 0; i < _length; i++) {