diff --git a/src/util/u_string.h b/src/util/u_string.h
index fb43ed0afc3..e4081466459 100644
--- a/src/util/u_string.h
+++ b/src/util/u_string.h
@@ -81,6 +81,7 @@ util_vsnprintf(char *str, size_t size, const char *format, va_list ap)
    if (ret < 0) {
       ret = _vscprintf(format, ap_copy);
    }
+   va_end(ap_copy);
    return ret;
 }