diff --git a/src/posix/cocoa/i_input.mm b/src/posix/cocoa/i_input.mm
index 98af16d80..786166a7b 100644
--- a/src/posix/cocoa/i_input.mm
+++ b/src/posix/cocoa/i_input.mm
@@ -473,6 +473,7 @@ void ProcessMouseMoveInMenu(NSEvent* theEvent)
 
 	event.type    = EV_GUI_Event;
 	event.subtype = EV_GUI_MouseMove;
+	event.data3   = ModifierFlagsToGUIKeyModifiers(theEvent);
 
 	NSEventToGameMousePosition(theEvent, &event);
 
@@ -633,7 +634,8 @@ void ProcessMouseButtonEvent(NSEvent* theEvent)
 
 	if (GUICapture)
 	{
-		event.type = EV_GUI_Event;
+		event.type  = EV_GUI_Event;
+		event.data3 = ModifierFlagsToGUIKeyModifiers(theEvent);
 
 		switch (cocoaEventType)
 		{