diff --git a/include/property.h b/include/property.h
index 77536aa4d..ba7d226cd 100644
--- a/include/property.h
+++ b/include/property.h
@@ -74,6 +74,7 @@ extern int ChangeWindowProperty(
     Bool /*sendevent*/);
 
 extern int DeleteProperty(
+    ClientPtr /*client*/,
     WindowPtr /*pWin*/,
     Atom /*propName*/);