diff --git a/lib/icinga/usergroup.cpp b/lib/icinga/usergroup.cpp
index 6ff4b89d4..49bd7186a 100644
--- a/lib/icinga/usergroup.cpp
+++ b/lib/icinga/usergroup.cpp
@@ -2,6 +2,7 @@
 
 #include "icinga/usergroup.hpp"
 #include "icinga/usergroup-ti.cpp"
+#include "icinga/notification.hpp"
 #include "config/objectrule.hpp"
 #include "config/configitem.hpp"
 #include "base/configtype.hpp"