64-bit safe
diff --git a/src/libflate/deflate.c b/src/libflate/deflate.c
index 3f5b69a..9e11af1 100644
--- a/src/libflate/deflate.c
+++ b/src/libflate/deflate.c
@@ -82,7 +82,7 @@
 /*
 #define hashit(c)	(((ulong)(c) * 0x6b43a9) >> (24 - HashLog))
 */
-#define hashit(c)	((((ulong)(c) & 0xffffff) * 0x6b43a9b5) >> (32 - HashLog))
+#define hashit(c)	(((((ulong)(c) & 0xffffff) * 0x6b43a9b5) >> (32 - HashLog)) & 0xFFFFFFFF)
 
 /*
  * lempel-ziv style compression state