1 files changed, 2 insertions, 2 deletions

diff --git a/adler32.c b/adler32.c
index a868f07..cfacc88 100644
--- a/adler32.c
+++ b/adler32.c
@@ -11,7 +11,7 @@
 
 local uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2));
 
-#define BASE 65521      /* largest prime smaller than 65536 */
+#define BASE 65521U     /* largest prime smaller than 65536 */
 #define NMAX 5552
 /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
 
@@ -156,7 +156,7 @@ local uLong adler32_combine_(adler1, adler2, len2)
     sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem;
     if (sum1 >= BASE) sum1 -= BASE;
     if (sum1 >= BASE) sum1 -= BASE;
-    if (sum2 >= (BASE << 1)) sum2 -= (BASE << 1);
+    if (sum2 >= ((unsigned long)BASE << 1)) sum2 -= ((unsigned long)BASE << 1);
     if (sum2 >= BASE) sum2 -= BASE;
     return sum1 | (sum2 << 16);
 }