diff --git a/src/libcharon/sa/ike_sa_manager.c b/src/libcharon/sa/ike_sa_manager.c
index 7763ae844e..d59fdb7f52 100644
--- a/src/libcharon/sa/ike_sa_manager.c
+++ b/src/libcharon/sa/ike_sa_manager.c
@@ -1151,6 +1151,7 @@ static status_t check_and_put_init_hash(private_ike_sa_manager_t *this,
 	spi = get_spi(this);
 	if (!spi)
 	{
+		mutex->unlock(mutex);
 		return FAILED;
 	}