diff --git a/includes/session.inc b/includes/session.inc
index 84d1983..ac8fce3 100644
--- a/includes/session.inc
+++ b/includes/session.inc
@@ -163,7 +163,7 @@ function _drupal_session_write($sid, $value) {
   try {
     if (!drupal_save_session()) {
       // We don't have anything to do if we are not allowed to save the session.
-      return;
+      return FALSE;
     }
 
     // Check whether $_SESSION has been changed in this request.
@@ -231,6 +231,7 @@ function _drupal_session_write($sid, $value) {
     }
     return FALSE;
   }
+  return TRUE;
 }
 
 /**
@@ -271,6 +272,7 @@ function drupal_session_initialize() {
     }
   }
   date_default_timezone_set(drupal_get_user_timezone());
+  return TRUE;
 }
 
 /**
@@ -292,6 +294,7 @@ function drupal_session_start() {
       $_SESSION += $session_data;
     }
   }
+  return TRUE;
 }
 
 /**
@@ -304,7 +307,7 @@ function drupal_session_commit() {
 
   if (!drupal_save_session()) {
     // We don't have anything to do if we are not allowed to save the session.
-    return;
+    return FALSE;
   }
 
   if (empty($user->uid) && empty($_SESSION)) {
@@ -329,6 +332,7 @@ function drupal_session_commit() {
     // Write the session data.
     session_write_close();
   }
+  return TRUE;
 }
 
 /**
@@ -351,7 +355,7 @@ function drupal_session_regenerate() {
   global $user, $is_https;
   // Nothing to do if we are not allowed to change the session.
   if (!drupal_save_session()) {
-    return;
+    return FALSE;
   }
 
   if ($is_https && variable_get('https', FALSE)) {
@@ -410,6 +414,7 @@ function drupal_session_regenerate() {
     $user = $account;
   }
   date_default_timezone_set(drupal_get_user_timezone());
+  return TRUE;
 }
 
 /**
@@ -425,7 +430,7 @@ function _drupal_session_destroy($sid) {
 
   // Nothing to do if we are not allowed to change the session.
   if (!drupal_save_session()) {
-    return;
+    return FALSE;
   }
 
   // Delete session data.
@@ -446,6 +451,7 @@ function _drupal_session_destroy($sid) {
   elseif (variable_get('https', FALSE)) {
     _drupal_session_delete_cookie('S' . session_name(), TRUE);
   }
+  return TRUE;
 }
 
 /**
@@ -466,6 +472,7 @@ function _drupal_session_delete_cookie($name, $secure = NULL) {
     setcookie($name, '', REQUEST_TIME - 3600, $params['path'], $params['domain'], $params['secure'], $params['httponly']);
     unset($_COOKIE[$name]);
   }
+  return TRUE;
 }
 
 /**
@@ -477,12 +484,14 @@ function _drupal_session_delete_cookie($name, $secure = NULL) {
 function drupal_session_destroy_uid($uid) {
   // Nothing to do if we are not allowed to change the session.
   if (!drupal_save_session()) {
-    return;
+    return FALSE;
   }
 
   db_delete('sessions')
     ->condition('uid', $uid)
     ->execute();
+
+  return TRUE;
 }
 
 /**