diff --git a/admin/tests/behat/webservice_users.feature b/admin/tests/behat/webservice_users.feature
index e334b0f0baf..5d466baf2be 100644
--- a/admin/tests/behat/webservice_users.feature
+++ b/admin/tests/behat/webservice_users.feature
@@ -1,4 +1,4 @@
-@core @core_admin
+@core @core_admin @core_webservice
 Feature: Web service user settings
   In order to configure authorised users for a web service
   As an admin
@@ -29,3 +29,13 @@ Feature: Web service user settings
     Then I should see "User One" in the ".alloweduserlist" "css_element"
     And I should see "1@example.org" in the ".alloweduserlist" "css_element"
     And I should see "Kermit" in the ".alloweduserlist" "css_element"
+
+  @javascript
+  Scenario: Add a function to a web service
+    When I log in as "admin"
+    And I navigate to "Server > Web services > External services" in site administration
+    And I click on "Functions" "link" in the "Silly service" "table_row"
+    And I follow "Add functions"
+    And I set the field "Name" to "core_blog_get_entries"
+    And I click on "Add functions" "button" in the "#fgroup_id_buttonar" "css_element"
+    Then I should see "core_blog_get_entries" in the "generaltable" "table"
diff --git a/admin/webservice/forms.php b/admin/webservice/forms.php
index 3060fd3fab9..4f15173f35c 100644
--- a/admin/webservice/forms.php
+++ b/admin/webservice/forms.php
@@ -196,7 +196,7 @@ class external_service_functions_form extends moodleform {
         //we add the descriptions to the functions
         foreach ($functions as $functionid => $functionname) {
             //retrieve full function information (including the description)
-            $function = external_api::external_function_info($functionname);
+            $function = \core_external\external_api::external_function_info($functionname);
             if (empty($function->deprecated)) {
                 $functions[$functionid] = $function->name . ':' . $function->description;
             } else {