diff --git a/rpn.go b/rpn.go
index 51686a7..8e3542f 100644
--- a/rpn.go
+++ b/rpn.go
@@ -16,7 +16,7 @@ func rpnNotify(w http.ResponseWriter, r *http.Request) {
 	}
 	ri, err := GetRpnInFromHTTPRequest(r) //ParseForm called
 	if err != nil {
-		errPage(w, http.StatusBadRequest, "invalid parameters")
+		errPage(w, http.StatusBadRequest, "invalid parameters "+err.Error())
 		return
 	}