diff --git a/src/alert_manager.cpp b/src/alert_manager.cpp
index a9fb5790a..44cb0d62a 100644
--- a/src/alert_manager.cpp
+++ b/src/alert_manager.cpp
@@ -147,7 +147,7 @@ namespace libtorrent
 		{
 			// never call a callback with the lock held!
 			lock.unlock();
-			m_notify();
+			if (m_notify) m_notify();
 		}
 	}