diff --git a/src/http/ngx_http_script.c b/src/http/ngx_http_script.c
index 8b861ce34..7c8de1445 100644
--- a/src/http/ngx_http_script.c
+++ b/src/http/ngx_http_script.c
@@ -265,7 +265,7 @@ ngx_http_test_predicates(ngx_http_request_t *r, ngx_array_t *predicates)
             return NGX_ERROR;
         }
 
-        if (val.len && val.data[0] != '0') {
+        if (val.len && (val.len != 1 || val.data[0] != '0')) {
             return NGX_DECLINED;
         }
     }