diff --git a/system/libraries/Session/drivers/Session_memcached_driver.php b/system/libraries/Session/drivers/Session_memcached_driver.php
index 760239d..9d7ab11 100644
--- a/system/libraries/Session/drivers/Session_memcached_driver.php
+++ b/system/libraries/Session/drivers/Session_memcached_driver.php
@@ -300,7 +300,10 @@
 	 */
 	protected function _get_lock($session_id)
 	{
-		if (isset($this->_lock_key))
+		// PHP 7 reuses the SessionHandler object on regeneration,
+		// so we need to check here if the lock key is for the
+		// correct session ID.
+		if ($this->_lock_key === $this->_key_prefix.$session_id.':lock')
 		{
 			return ($this->_memcached->replace($this->_lock_key, time(), 300))
 				? $this->_success
diff --git a/system/libraries/Session/drivers/Session_redis_driver.php b/system/libraries/Session/drivers/Session_redis_driver.php
index b60ef6b..a31c453 100644
--- a/system/libraries/Session/drivers/Session_redis_driver.php
+++ b/system/libraries/Session/drivers/Session_redis_driver.php
@@ -314,7 +314,10 @@
 	 */
 	protected function _get_lock($session_id)
 	{
-		if (isset($this->_lock_key))
+		// PHP 7 reuses the SessionHandler object on regeneration,
+		// so we need to check here if the lock key is for the
+		// correct session ID.
+		if ($this->_lock_key === $this->_key_prefix.$session_id.':lock')
 		{
 			return $this->_redis->setTimeout($this->_lock_key, 300);
 		}