diff --git a/src/Tiny_httpd.ml b/src/Tiny_httpd.ml
index 73751c5c..b87b8e53 100644
--- a/src/Tiny_httpd.ml
+++ b/src/Tiny_httpd.ml
@@ -457,7 +457,9 @@ module Request = struct
       let line = Byte_stream.read_line ~buf bs in
       let meth, path =
         try Scanf.sscanf line "%s %s HTTP/1.1\r" (fun x y->x,y)
-        with _ -> raise (Bad_req (400, "Invalid request line"))
+      with _ ->
+        _debug (fun k->k "invalid request line: `%s`" line);
+        raise (Bad_req (400, "Invalid request line"))
       in
       let meth = Meth.of_string meth in
       _debug (fun k->k "got meth: %s, path %S" (Meth.to_string meth) path);