diff --git a/mod/assign/extensionform.php b/mod/assign/extensionform.php
index f838638adfc..0b39697e3e7 100644
--- a/mod/assign/extensionform.php
+++ b/mod/assign/extensionform.php
@@ -69,9 +69,13 @@ class mod_assign_extension_form extends moodleform {
                            get_string('extensionduedate', 'assign'), array('optional'=>true));
         $mform->setDefault('extensionduedate', $finaldate);
         $mform->addElement('hidden', 'id', $coursemoduleid);
+        $mform->setType('id', PARAM_INT);
         $mform->addElement('hidden', 'userid', $userid);
+        $mform->setType('userid', PARAM_INT);
         $mform->addElement('hidden', 'selectedusers', $batchusers);
+        $mform->setType('selectedusers', PARAM_SEQUENCE);
         $mform->addElement('hidden', 'action', 'saveextension');
+        $mform->setType('action', PARAM_ALPHA);
         $this->add_action_buttons(true, get_string('savechanges', 'assign'));
 
         if ($data) {
diff --git a/mod/assign/feedback/file/batchuploadfilesform.php b/mod/assign/feedback/file/batchuploadfilesform.php
index a0beb1722d1..c025ee8d8d1 100644
--- a/mod/assign/feedback/file/batchuploadfilesform.php
+++ b/mod/assign/feedback/file/batchuploadfilesform.php
@@ -66,12 +66,19 @@ class assignfeedback_file_batch_upload_files_form extends moodleform {
         $this->set_data($data);
 
         $mform->addElement('hidden', 'id', $params['cm']);
+        $mform->setType('id', PARAM_INT);
         $mform->addElement('hidden', 'operation', 'plugingradingbatchoperation_file_uploadfiles');
+        $mform->setType('operation', PARAM_ALPHAEXT);
         $mform->addElement('hidden', 'action', 'viewpluginpage');
+        $mform->setType('action', PARAM_ALPHA);
         $mform->addElement('hidden', 'pluginaction', 'uploadfiles');
+        $mform->setType('pluginaction', PARAM_ALPHA);
         $mform->addElement('hidden', 'plugin', 'file');
+        $mform->setType('plugin', PARAM_PLUGIN);
         $mform->addElement('hidden', 'pluginsubtype', 'assignfeedback');
+        $mform->setType('pluginsubtype', PARAM_PLUGIN);
         $mform->addElement('hidden', 'selectedusers', implode(',', $params['users']));
+        $mform->setType('selectedusers', PARAM_SEQUENCE);
         $this->add_action_buttons(true, get_string('uploadfiles', 'assignfeedback_file'));
 
     }
diff --git a/mod/assign/feedback/file/importzipform.php b/mod/assign/feedback/file/importzipform.php
index 33e75020315..4ed2bfa5d57 100644
--- a/mod/assign/feedback/file/importzipform.php
+++ b/mod/assign/feedback/file/importzipform.php
@@ -115,11 +115,17 @@ class assignfeedback_file_import_zip_form extends moodleform implements renderab
         }
 
         $mform->addElement('hidden', 'id', $assignment->get_course_module()->id);
+        $mform->setType('id', PARAM_INT);
         $mform->addElement('hidden', 'action', 'viewpluginpage');
+        $mform->setType('action', PARAM_ALPHA);
         $mform->addElement('hidden', 'confirm', 'true');
+        $mform->setType('confirm', PARAM_BOOL);
         $mform->addElement('hidden', 'plugin', 'file');
+        $mform->setTYpe('plugin', PARAM_PLUGIN);
         $mform->addElement('hidden', 'pluginsubtype', 'assignfeedback');
+        $mform->setTYpe('pluginsubtype', PARAM_PLUGIN);
         $mform->addElement('hidden', 'pluginaction', 'uploadzip');
+        $mform->setType('pluginaction', PARAM_ALPHA);
         if (count($updates)) {
             $this->add_action_buttons(true, get_string('confirm'));
         } else {
diff --git a/mod/assign/feedback/file/locallib.php b/mod/assign/feedback/file/locallib.php
index e0b6281a7fe..50c0e25ab4e 100644
--- a/mod/assign/feedback/file/locallib.php
+++ b/mod/assign/feedback/file/locallib.php
@@ -590,7 +590,7 @@ class assign_feedback_file extends assign_feedback_plugin {
      */
     public function view_page($action) {
         if ($action == 'uploadfiles') {
-            $users = required_param('selectedusers', PARAM_TEXT);
+            $users = required_param('selectedusers', PARAM_SEQUENCE);
             return $this->view_batch_upload_files(explode(',', $users));
         }
         if ($action == 'uploadzip') {
diff --git a/mod/assign/feedback/file/uploadzipform.php b/mod/assign/feedback/file/uploadzipform.php
index d9e7636772b..4d521307ccc 100644
--- a/mod/assign/feedback/file/uploadzipform.php
+++ b/mod/assign/feedback/file/uploadzipform.php
@@ -56,10 +56,15 @@ class assignfeedback_file_upload_zip_form extends moodleform {
         $mform->addHelpButton('feedbackzip', 'feedbackzip', 'assignfeedback_file');
 
         $mform->addElement('hidden', 'id', $params['cm']);
+        $mform->setType('id', PARAM_INT);
         $mform->addElement('hidden', 'action', 'viewpluginpage');
+        $mform->setType('action', PARAM_ALPHA);
         $mform->addElement('hidden', 'pluginaction', 'uploadzip');
+        $mform->setType('pluginaction', PARAM_ALPHA);
         $mform->addElement('hidden', 'plugin', 'file');
+        $mform->setType('plugin', PARAM_PLUGIN);
         $mform->addElement('hidden', 'pluginsubtype', 'assignfeedback');
+        $mform->setType('pluginsubtype', PARAM_PLUGIN);
         $this->add_action_buttons(true, get_string('importfeedbackfiles', 'assignfeedback_file'));
 
     }
diff --git a/mod/assign/feedback/offline/importgradesform.php b/mod/assign/feedback/offline/importgradesform.php
index e3ac2e49a45..b71bd5402f3 100644
--- a/mod/assign/feedback/offline/importgradesform.php
+++ b/mod/assign/feedback/offline/importgradesform.php
@@ -164,14 +164,23 @@ class assignfeedback_offline_import_grades_form extends moodleform implements re
         }
 
         $mform->addElement('hidden', 'id', $assignment->get_course_module()->id);
+        $mform->setType('id', PARAM_INT);
         $mform->addElement('hidden', 'action', 'viewpluginpage');
+        $mform->setType('action', PARAM_ALPHA);
         $mform->addElement('hidden', 'confirm', 'true');
+        $mform->setType('confirm', PARAM_BOOL);
         $mform->addElement('hidden', 'plugin', 'offline');
+        $mform->setType('plugin', PARAM_PLUGIN);
         $mform->addElement('hidden', 'pluginsubtype', 'assignfeedback');
+        $mform->setType('pluginsubtype', PARAM_PLUGIN);
         $mform->addElement('hidden', 'pluginaction', 'uploadgrades');
+        $mform->setType('pluginaction', PARAM_ALPHA);
         $mform->addElement('hidden', 'importid', $gradeimporter->importid);
+        $mform->setType('importid', PARAM_INT);
         $mform->addElement('hidden', 'ignoremodified', $ignoremodified);
+        $mform->setType('ignoremodified', PARAM_BOOL);
         $mform->addElement('hidden', 'draftid', $draftid);
+        $mform->setType('draftid', PARAM_INT);
         if ($update) {
             $this->add_action_buttons(true, get_string('confirm'));
         } else {
diff --git a/mod/assign/feedback/offline/uploadgradesform.php b/mod/assign/feedback/offline/uploadgradesform.php
index c573efe864c..75355cf9e4c 100644
--- a/mod/assign/feedback/offline/uploadgradesform.php
+++ b/mod/assign/feedback/offline/uploadgradesform.php
@@ -59,10 +59,15 @@ class assignfeedback_offline_upload_grades_form extends moodleform {
         $mform->addHelpButton('ignoremodified', 'ignoremodified', 'assignfeedback_offline');
 
         $mform->addElement('hidden', 'id', $params['cm']);
+        $mform->setType('id', PARAM_INT);
         $mform->addElement('hidden', 'action', 'viewpluginpage');
+        $mform->setType('action', PARAM_ALPHA);
         $mform->addElement('hidden', 'pluginaction', 'uploadgrades');
+        $mform->setType('pluginaction', PARAM_ALPHA);
         $mform->addElement('hidden', 'plugin', 'offline');
+        $mform->setType('plugin', PARAM_PLUGIN);
         $mform->addElement('hidden', 'pluginsubtype', 'assignfeedback');
+        $mform->setType('pluginsubtype', PARAM_PLUGIN);
         $this->add_action_buttons(true, get_string('uploadgrades', 'assignfeedback_offline'));
 
     }
diff --git a/mod/assign/gradingbatchoperationsform.php b/mod/assign/gradingbatchoperationsform.php
index d9f74a9617f..4be18c35104 100644
--- a/mod/assign/gradingbatchoperationsform.php
+++ b/mod/assign/gradingbatchoperationsform.php
@@ -66,9 +66,13 @@ class mod_assign_grading_batch_operations_form extends moodleform {
         }
 
         $mform->addElement('hidden', 'action', 'gradingbatchoperation');
+        $mform->setType('action', PARAM_ALPHA);
         $mform->addElement('hidden', 'id', $instance['cm']);
+        $mform->setType('id', PARAM_INT);
         $mform->addElement('hidden', 'selectedusers', '', array('class'=>'selectedusers'));
+        $mform->setType('selectedusers', PARAM_SEQUENCE);
         $mform->addElement('hidden', 'returnaction', 'grading');
+        $mform->setType('returnaction', PARAM_ALPHA);
 
         $objs = array();
         $objs[] =& $mform->createElement('select', 'operation', get_string('chooseoperation', 'assign'), $options);
diff --git a/mod/assign/locallib.php b/mod/assign/locallib.php
index 7e9ff3021e1..528d5b9a266 100644
--- a/mod/assign/locallib.php
+++ b/mod/assign/locallib.php
@@ -1730,7 +1730,7 @@ class assign {
         require_once($CFG->dirroot . '/mod/assign/extensionform.php');
 
         $o = '';
-        $batchusers = optional_param('selectedusers', '', PARAM_TEXT);
+        $batchusers = optional_param('selectedusers', '', PARAM_SEQUENCE);
         $data = new stdClass();
         $data->extensionduedate = null;
         $userid = 0;
@@ -4295,7 +4295,7 @@ class assign {
         // Need submit permission to submit an assignment.
         require_capability('mod/assign:grantextension', $this->context);
 
-        $batchusers = optional_param('selectedusers', '', PARAM_TEXT);
+        $batchusers = optional_param('selectedusers', '', PARAM_SEQUENCE);
         $userid = 0;
         if (!$batchusers) {
             $userid = required_param('userid', PARAM_INT);
diff --git a/mod/assign/mod_form.php b/mod/assign/mod_form.php
index 6d232f2f889..f2d60e9dee2 100644
--- a/mod/assign/mod_form.php
+++ b/mod/assign/mod_form.php
@@ -117,6 +117,7 @@ class mod_assign_mod_form extends moodleform_mod {
         } else {
             $mform->addElement('hidden', 'requiresubmissionstatement', 1);
         }
+        $mform->setType('requiresubmissionstatement', PARAM_BOOL);
 
         $options = array(
             ASSIGN_ATTEMPT_REOPEN_METHOD_NONE => get_string('attemptreopenmethod_none', 'mod_assign'),