diff --git a/vm/vm_unix.c b/vm/vm_unix.c
--- a/vm/vm_unix.c
+++ b/vm/vm_unix.c
@@ -91,7 +91,7 @@
 	 * in the data space if the DATA rlimit is raised on the running
 	 * program.
 	 */
-	if (incr < 0) {
+	if ((intptr_t)incr < 0) {
 		error = EOPNOTSUPP;
 		goto done;
 	}