diff --git a/http.c b/http.c
index d843bb5..fc9ed0e 100644
--- a/http.c
+++ b/http.c
@@ -260,7 +260,7 @@ static int parse_args(struct ctx *const c, const char *const res,
 {
     int error;
     const char *const arg_start = strchr(res, '?'),
-        *const ad_arg = strchr(res, '&');
+        *const ad_arg = arg_start ? strchr(res, '&') : NULL;
 
     if (!arg_start)
     {