diff --git a/slirp/cksum.c b/slirp/cksum.c
index e43867da37..63286600e7 100644
--- a/slirp/cksum.c
+++ b/slirp/cksum.c
@@ -75,7 +75,7 @@ int cksum(struct mbuf *m, int len)
 	/*
 	 * Force to even boundary.
 	 */
-	if ((1 & (long) w) && (mlen > 0)) {
+	if ((1 & (uintptr_t)w) && (mlen > 0)) {
 		REDUCE;
 		sum <<= 8;
 		s_util.c[0] = *(uint8_t *)w;