diff --git a/util/cutils.c b/util/cutils.c
index d682c90901..9aacc422ca 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -683,7 +683,7 @@ int parse_uint(const char *s, unsigned long long *value, char **endptr,
     }
 
     /* make sure we reject negative numbers: */
-    while (isspace((unsigned char)*s)) {
+    while (qemu_isspace(*s)) {
         s++;
     }
     if (*s == '-') {