diff --git a/auth/saml/auth.php b/auth/saml/auth.php
index 1fe0b83..2769f9b 100755
--- a/auth/saml/auth.php
+++ b/auth/saml/auth.php
@@ -26,12 +26,39 @@
 **/
 class auth_plugin_saml extends auth_plugin_base {
 
+    /**
+     * The SP.
+     */
+    protected static $sp;
+
+    /**
+     * Are we currently forcing log-out?
+     */
+    protected static $forcingLogout = FALSE;
+
     /**
     * Constructor.
     */
     function auth_plugin_saml() {
-		$this->authtype = 'saml';
-		$this->config = get_config('auth/saml');
+        $this->authtype = 'saml';
+        $this->config = get_config('auth/saml');
+        // Include the autoloader since Moodle isn't a composer project itself.
+        require_once($this->config->samllib . '/_autoload.php');
+        if (empty(static::$sp)) {
+            static::$sp = new SimpleSAML_Auth_Simple($this->config->sp_source);
+        }
+        // Additionally determine if the user is still logged in to the SP.
+        global $USER;
+        global $SESSION;
+            if ($USER->loggedin && $USER->auth == "saml") {
+                if (!static::$forcingLogout
+                    && (!static::$sp->isAuthenticated()
+                    || (static::$sp->getAuthData('saml:sp:NameID') != $SESSION->auth_saml['NameID']))) {
+                    // The user is logged in with the saml module but doesn't share a session on the SP.
+                    static::$forcingLogout = TRUE;
+                    require_logout();
+                }
+            }
     }
 
     /**
diff --git a/auth/saml/index.php b/auth/saml/index.php
index 99166c7..fd0b155 100755
--- a/auth/saml/index.php
+++ b/auth/saml/index.php
@@ -207,7 +207,7 @@
 
         $USER = complete_user_login($user);
 
-        if (function_exists('saml_hook_post_user_created')) {
+        if (function_exists('saml_hook_post_user_created') && !$user_exists && $USER->id) {
             saml_hook_post_user_created($USER);
         }
 
@@ -218,6 +218,7 @@
         $USER->loggedin = true;
         $USER->site = $CFG->wwwroot;
         set_moodle_cookie($USER->username);
+        $SESSION->auth_saml['NameID'] = $as->getAuthData('saml:sp:NameID');
 
         if(isset($err) && !empty($err)) {
             auth_saml_error($err, $urltogo, $pluginconfig->samllogfile);