diff --git a/libs/surfaces/osc/MSVCardour_osc/ardour_osc.vcproj b/libs/surfaces/osc/MSVCardour_osc/ardour_osc.vcproj
index b3faa4bc3d..c1d664e2e8 100644
--- a/libs/surfaces/osc/MSVCardour_osc/ardour_osc.vcproj
+++ b/libs/surfaces/osc/MSVCardour_osc/ardour_osc.vcproj
@@ -313,6 +313,10 @@
 				RelativePath="..\osc_global_observer.h"
 				>
 			</File>
+			<File
+				RelativePath="..\osc_gui.h"
+				>
+			</File>
 			<File
 				RelativePath="..\osc_route_observer.h"
 				>