diff --git a/classes/external.php b/classes/external.php
index dd67112e..3e18af60 100644
--- a/classes/external.php
+++ b/classes/external.php
@@ -31,11 +31,13 @@
 
 require_once("$CFG->libdir/externallib.php");
 
+use context_module;
 use external_api;
 use external_function_parameters;
 use external_single_structure;
 use external_value;
 use external_warnings;
+use invalid_response_exception;
 
 /**
  * Zoom external functions