diff --git a/src/IsrCallback.h b/src/IsrCallback.h
index 2f1a38d5..aaf4455b 100644
--- a/src/IsrCallback.h
+++ b/src/IsrCallback.h
@@ -18,6 +18,8 @@ class IsrCallback
 static void generic_callback_isr (void* data)
 {
     IsrCallback* callback = (IsrCallback*) data;
+    if (callback == NULL)
+        return;
     callback->run();
 }
 #endif