diff --git a/lib/form/recaptcha.php b/lib/form/recaptcha.php
index 2080088..41c313f 100644
--- a/lib/form/recaptcha.php
+++ b/lib/form/recaptcha.php
@@ -42,9 +42,6 @@ class MoodleQuickForm_recaptcha extends HTML_QuickForm_input {
     /** @var string html for help button, if empty then no help */
     var $_helpbutton='';
 
-    /** @var bool if true, recaptcha will be servered from https */
-    var $_https=false;
-
     /**
      * constructor
      *
@@ -54,14 +51,10 @@ class MoodleQuickForm_recaptcha extends HTML_QuickForm_input {
      *              or an associative array
      */
     function MoodleQuickForm_recaptcha($elementName = null, $elementLabel = null, $attributes = null) {
-        global $CFG;
+        global $CFG, $PAGE;
+        $PAGE->requires->js(new moodle_url('https://www.google.com/recaptcha/api.js'), true);
         parent::HTML_QuickForm_input($elementName, $elementLabel, $attributes);
         $this->_type = 'recaptcha';
-        if (is_https()) {
-            $this->_https = true;
-        } else {
-            $this->_https = false;
-        }
     }
 
     /**
@@ -70,44 +63,8 @@ class MoodleQuickForm_recaptcha extends HTML_QuickForm_input {
      * @return string
      */
     function toHtml() {
-        global $CFG, $PAGE;
-        require_once $CFG->libdir . '/recaptchalib.php';
-
-        $recaptureoptions = Array('theme'=>'custom', 'custom_theme_widget'=>'recaptcha_widget');
-        $html = html_writer::script(js_writer::set_variable('RecaptchaOptions', $recaptureoptions));
-
-        $attributes = $this->getAttributes();
-        if (empty($attributes['error_message'])) {
-            $attributes['error_message'] = null;
-            $this->setAttributes($attributes);
-        }
-        $error = $attributes['error_message'];
-        unset($attributes['error_message']);
-
-        $strincorrectpleasetryagain = get_string('incorrectpleasetryagain', 'auth');
-        $strenterthewordsabove = get_string('enterthewordsabove', 'auth');
-        $strenterthenumbersyouhear = get_string('enterthenumbersyouhear', 'auth');
-        $strgetanothercaptcha = get_string('getanothercaptcha', 'auth');
-        $strgetanaudiocaptcha = get_string('getanaudiocaptcha', 'auth');
-        $strgetanimagecaptcha = get_string('getanimagecaptcha', 'auth');
-
-        $html .= '
-<div id="recaptcha_widget" style="display:none">
-
-<div id="recaptcha_image"></div>
-<div class="recaptcha_only_if_incorrect_sol" style="color:red">' . $strincorrectpleasetryagain . '</div>
-
-<span class="recaptcha_only_if_image"><label for="recaptcha_response_field">' . $strenterthewordsabove . '</label></span>
-<span class="recaptcha_only_if_audio"><label for="recaptcha_response_field">' . $strenterthenumbersyouhear . '</label></span>
-
-<input type="text" id="recaptcha_response_field" name="recaptcha_response_field" />
-<input type="hidden" name="recaptcha_element" value="dummyvalue" /> <!-- Dummy value to fool formslib -->
-<div><a href="javascript:Recaptcha.reload()">' . $strgetanothercaptcha . '</a></div>
-<div class="recaptcha_only_if_image"><a href="javascript:Recaptcha.switch_type(\'audio\')">' . $strgetanaudiocaptcha . '</a></div>
-<div class="recaptcha_only_if_audio"><a href="javascript:Recaptcha.switch_type(\'image\')">' . $strgetanimagecaptcha . '</a></div>
-</div>';
-
-        return $html . recaptcha_get_html($CFG->recaptchapublickey, $error, $this->_https);
+        global $CFG;
+        return html_writer::empty_tag('div', array('class'=>'g-recaptcha', 'data-sitekey'=> $CFG->recaptchapublickey));
     }
 
     /**
@@ -120,26 +77,29 @@ class MoodleQuickForm_recaptcha extends HTML_QuickForm_input {
     }
 
     /**
-     * Checks input and challenged field
+     * Checks recaptcha response with google.
      *
-     * @param string $challenge_field recaptcha shown  to user
-     * @param string $response_field input value by user
+     * @param string $responsestr
      * @return bool
      */
-    function verify($challenge_field, $response_field) {
+    function is_recaptcha_response_valid($responsestr) {
         global $CFG;
-        require_once $CFG->libdir . '/recaptchalib.php';
-        $response = recaptcha_check_answer($CFG->recaptchaprivatekey,
-                                           getremoteaddr(),
-                                           $challenge_field,
-                                           $response_field,
-                                           $this->_https);
-        if (!$response->is_valid) {
-            $attributes = $this->getAttributes();
-            $attributes['error_message'] = $response->error;
-            $this->setAttributes($attributes);
-            return $response->error;
+        require_once($CFG->libdir.'/filelib.php');
+
+        $remoteip = getremoteaddr();
+        $params = "secret={$CFG->recaptchaprivatekey}&response={$responsestr}&remoteip={$remoteip}";
+        $curl = new curl();
+        $url = 'https://www.google.com/recaptcha/api/siteverify';
+        $response = $curl->post($url, $params);
+
+        if ($curl->errno == 0) {
+            $data = json_decode($response);
+
+            if (isset($data->success) && $data->success == 'true') {
+                return true;
+            }
         }
-        return true;
+
+        return false;
     }
 }
diff --git a/login/signup_form.php b/login/signup_form.php
index 71ad670..ef08ed2 100644
--- a/login/signup_form.php
+++ b/login/signup_form.php
@@ -164,18 +164,19 @@ class login_signup_form extends moodleform {
             $errors['password'] = $errmsg;
         }
 
+        // BEGIN moodle.org hack (MDLSITE-3878)
         if ($this->signup_captcha_enabled()) {
             $recaptcha_element = $this->_form->getElement('recaptcha_element');
-            if (!empty($this->_form->_submitValues['recaptcha_challenge_field'])) {
-                $challenge_field = $this->_form->_submitValues['recaptcha_challenge_field'];
-                $response_field = $this->_form->_submitValues['recaptcha_response_field'];
-                if (true !== ($result = $recaptcha_element->verify($challenge_field, $response_field))) {
-                    $errors['recaptcha'] = $result;
+            if (!empty($this->_form->_submitValues['g-recaptcha-response'])) {
+                $response = $this->_form->_submitValues['g-recaptcha-response'];
+                if (!$recaptcha_element->is_recaptcha_response_valid($response)) {
+                    $errors['recaptcha_element'] = get_string('invaliddata', 'error');
                 }
             } else {
-                $errors['recaptcha'] = get_string('missingrecaptchachallengefield');
+                $errors['recaptcha_element'] = get_string('missingrecaptchachallengefield');
             }
         }
+        // END moodle.org hack (MDLSITE-3878)
         // Validate customisable profile fields. (profile_validation expects an object as the parameter with userid set)
         $dataobject = (object)$data;
         $dataobject->id = 0;