diff --git a/common/cmd_itest.c b/common/cmd_itest.c
index ae2527b..76af62b 100644
--- a/common/cmd_itest.c
+++ b/common/cmd_itest.c
@@ -63,7 +63,7 @@ static long evalexp(char *s, int w)
 		l = simple_strtoul(s, NULL, 16);
 	}
 
-	return (l & ((1 << (w * 8)) - 1));
+	return l & ((1UL << (w * 8)) - 1);
 }
 
 static char * evalstr(char *s)