diff --git a/course/mod.php b/course/mod.php
index 54f6f9cb5a293..67719a7aae2c4 100644
--- a/course/mod.php
+++ b/course/mod.php
@@ -27,7 +27,7 @@
 require_once("lib.php");
 
 $sectionreturn = optional_param('sr', null, PARAM_INT);
-$add           = optional_param('add', '', PARAM_ALPHA);
+$add           = optional_param('add', '', PARAM_ALPHANUM);
 $type          = optional_param('type', '', PARAM_ALPHA);
 $indent        = optional_param('indent', 0, PARAM_INT);
 $update        = optional_param('update', 0, PARAM_INT);
diff --git a/course/modedit.php b/course/modedit.php
index f048bcd25e43a..0388708c9a06c 100644
--- a/course/modedit.php
+++ b/course/modedit.php
@@ -31,7 +31,7 @@
 require_once($CFG->libdir.'/plagiarismlib.php');
 require_once($CFG->dirroot . '/course/modlib.php');
 
-$add    = optional_param('add', '', PARAM_ALPHA);     // module name
+$add    = optional_param('add', '', PARAM_ALPHANUM);     // Module name.
 $update = optional_param('update', 0, PARAM_INT);
 $return = optional_param('return', 0, PARAM_BOOL);    //return to course/view.php if false or mod/modname/view.php if true
 $type   = optional_param('type', '', PARAM_ALPHANUM); //TODO: hopefully will be removed in 2.0
diff --git a/course/moodleform_mod.php b/course/moodleform_mod.php
index 34c25f04735c7..2bbdac012dcee 100644
--- a/course/moodleform_mod.php
+++ b/course/moodleform_mod.php
@@ -942,7 +942,7 @@ function standard_hidden_coursemodule_elements(){
         $mform->setType('instance', PARAM_INT);
 
         $mform->addElement('hidden', 'add', 0);
-        $mform->setType('add', PARAM_ALPHA);
+        $mform->setType('add', PARAM_ALPHANUM);
 
         $mform->addElement('hidden', 'update', 0);
         $mform->setType('update', PARAM_INT);
diff --git a/course/upgrade.txt b/course/upgrade.txt
index f88a58bb4f759..195a6ebf7fc55 100644
--- a/course/upgrade.txt
+++ b/course/upgrade.txt
@@ -4,6 +4,7 @@ information provided here is intended especially for developers.
 === 3.9 ===
 
 * The function get_module_metadata is now deprecated. Please use \core_course\local\service\content_item_service instead.
+* Activity module names are now PARAM_ALPHANUM instead of PARAM_ALPHA so integers can be used in activity module names
 
 === 3.8 ===