diff --git a/admin/tool/mobile/launch.php b/admin/tool/mobile/launch.php
index 1e74e37fc32..2c5fc181b50 100644
--- a/admin/tool/mobile/launch.php
+++ b/admin/tool/mobile/launch.php
@@ -30,7 +30,7 @@ require_once($CFG->libdir . '/externallib.php');
 
 $serviceshortname  = required_param('service',  PARAM_ALPHANUMEXT);
 $passport          = required_param('passport',  PARAM_RAW);    // Passport send from the app to validate the response URL.
-$urlscheme         = optional_param('urlscheme', 'moodlemobile', PARAM_NOTAGS); // The URL scheme the app supports.
+$urlscheme         = optional_param('urlscheme', 'moodlemobile', PARAM_ALPHANUM); // The URL scheme the app supports.
 $confirmed         = optional_param('confirmed', false, PARAM_BOOL);  // If we are being redirected after user confirmation.
 $oauthsso          = optional_param('oauthsso', 0, PARAM_INT); // Id of the OpenID issuer (for OAuth direct SSO).
 
diff --git a/admin/tool/mobile/settings.php b/admin/tool/mobile/settings.php
index 125a72a6929..6b5d634b36f 100644
--- a/admin/tool/mobile/settings.php
+++ b/admin/tool/mobile/settings.php
@@ -63,7 +63,7 @@ if ($hassiteconfig) {
 
         $temp->add(new admin_setting_configtext('tool_mobile/forcedurlscheme',
                     new lang_string('forcedurlscheme_key', 'tool_mobile'),
-                    new lang_string('forcedurlscheme', 'tool_mobile'), '', PARAM_NOTAGS));
+                    new lang_string('forcedurlscheme', 'tool_mobile'), '', PARAM_ALPHANUM));
 
         $ADMIN->add('mobileapp', $temp);