diff --git a/src/BufferView_pimpl.h b/src/BufferView_pimpl.h
index 5ba3484684..20f131c789 100644
--- a/src/BufferView_pimpl.h
+++ b/src/BufferView_pimpl.h
@@ -25,6 +25,7 @@
 #include "insets/inset.h"
 
 #include "frontends/key_state.h"
+#include "frontends/LyXKeySym.h"
 #include "frontends/Timeout.h"
 
 #include "support/types.h"