diff --git a/dlls/comctl32/monthcal.c b/dlls/comctl32/monthcal.c
index 5a34a37c1b2..893a5056059 100644
--- a/dlls/comctl32/monthcal.c
+++ b/dlls/comctl32/monthcal.c
@@ -1138,6 +1138,8 @@ MONTHCAL_SetFirstDayOfWeek(MONTHCAL_INFO *infoPtr, INT day)
     infoPtr->firstDayHighWord = TRUE;
   }
 
+  InvalidateRect(infoPtr->hwndSelf, NULL, FALSE);
+
   return prev;
 }