diff --git a/lib/form/password.php b/lib/form/password.php
index c157a47fad6..cfe1d7544df 100644
--- a/lib/form/password.php
+++ b/lib/form/password.php
@@ -19,9 +19,14 @@ class MoodleQuickForm_password extends HTML_QuickForm_password{
         if (empty($CFG->xmlstrictheaders)) {
             // no standard mform in moodle should allow autocomplete of passwords
             // this is valid attribute in html5, sorry, we have to ignore validation errors in legacy xhtml 1.0
-            $attributes = (array)$attributes;
-            if (!isset($attributes['autocomplete'])) {
+            if (empty($attributes)) {
+                $attributes = array('autocomplete'=>'off');
+            } else if (is_array($attributes)) {
                 $attributes['autocomplete'] = 'off';
+            } else {
+                if (strpos($attributes, 'autocomplete') === false) {
+                    $attributes .= ' autocomplete="off" ';
+                }
             }
         }
 
diff --git a/lib/form/passwordunmask.php b/lib/form/passwordunmask.php
index 7210323536e..40e087e1fd6 100644
--- a/lib/form/passwordunmask.php
+++ b/lib/form/passwordunmask.php
@@ -19,9 +19,14 @@ class MoodleQuickForm_passwordunmask extends MoodleQuickForm_password {
         if (empty($CFG->xmlstrictheaders)) {
             // no standard mform in moodle should allow autocomplete of passwords
             // this is valid attribute in html5, sorry, we have to ignore validation errors in legacy xhtml 1.0
-            $attributes = (array)$attributes;
-            if (!isset($attributes['autocomplete'])) {
+            if (empty($attributes)) {
+                $attributes = array('autocomplete'=>'off');
+            } else if (is_array($attributes)) {
                 $attributes['autocomplete'] = 'off';
+            } else {
+                if (strpos($attributes, 'autocomplete') === false) {
+                    $attributes .= ' autocomplete="off" ';
+                }
             }
         }
         parent::MoodleQuickForm_password($elementName, $elementLabel, $attributes);
diff --git a/lib/formslib.php b/lib/formslib.php
index e816da60b56..003e1211017 100644
--- a/lib/formslib.php
+++ b/lib/formslib.php
@@ -143,9 +143,14 @@ abstract class moodleform {
         if (empty($CFG->xmlstrictheaders)) {
             // no standard mform in moodle should allow autocomplete with the exception of user signup
             // this is valid attribute in html5, sorry, we have to ignore validation errors in legacy xhtml 1.0
-            $attributes = (array)$attributes;
-            if (!isset($attributes['autocomplete'])) {
+            if (empty($attributes)) {
+                $attributes = array('autocomplete'=>'off');
+            } else if (is_array($attributes)) {
                 $attributes['autocomplete'] = 'off';
+            } else {
+                if (strpos($attributes, 'autocomplete') === false) {
+                    $attributes .= ' autocomplete="off" ';
+                }
             }
         }