diff --git a/util/json.c b/util/json.c
index 1d5c6bc7..ba9daa35 100644
--- a/util/json.c
+++ b/util/json.c
@@ -75,7 +75,7 @@ static int display_size(struct json_object *jobj, struct printbuf *pbuf,
 static int display_hex(struct json_object *jobj, struct printbuf *pbuf,
 		int level, int flags)
 {
-	unsigned long long val = json_object_get_int64(jobj);
+	unsigned long long val = util_json_get_u64(jobj);
 	static char buf[32];
 
 	snprintf(buf, sizeof(buf), "\"%#llx\"", val);
diff --git a/util/json.h b/util/json.h
index ea370df4..a8d02838 100644
--- a/util/json.h
+++ b/util/json.h
@@ -34,10 +34,18 @@ static inline struct json_object *util_json_new_u64(unsigned long long val)
 {
 	return json_object_new_uint64(val);
 }
+static inline unsigned long long util_json_get_u64(struct json_object *jobj)
+{
+	return json_object_get_uint64(jobj);
+}
 #else /* fallback to signed */
 static inline struct json_object *util_json_new_u64(unsigned long long val)
 {
 	return json_object_new_int64(val);
 }
+static inline unsigned long long util_json_get_u64(struct json_object *jobj)
+{
+	return json_object_get_int64(jobj);
+}
 #endif /* HAVE_JSON_U64 */
 #endif /* __UTIL_JSON_H__ */