diff --git a/include/knowrob/storage/mongo/ChangeStream.h b/include/knowrob/storage/mongo/ChangeStream.h
index fc3f471f68..8010042fc9 100644
--- a/include/knowrob/storage/mongo/ChangeStream.h
+++ b/include/knowrob/storage/mongo/ChangeStream.h
@@ -8,6 +8,7 @@
 
 #include <mongoc.h>
 #include <string>
+#include <functional>
 #include <memory>
 #include "Collection.h"
 #include "bson.h"