diff --git a/src/http/ngx_http_parse.c b/src/http/ngx_http_parse.c
index 8e1b11852..b8a27e084 100644
--- a/src/http/ngx_http_parse.c
+++ b/src/http/ngx_http_parse.c
@@ -1561,6 +1561,10 @@ ngx_http_parse_complex_uri(ngx_http_request_t *r, ngx_uint_t merge_slashes)
         }
     }
 
+    if (state == sw_quoted || state == sw_quoted_second) {
+        return NGX_HTTP_PARSE_INVALID_REQUEST;
+    }
+
 done:
 
     r->uri.len = u - r->uri.data;