diff --git a/Xi/exevents.c b/Xi/exevents.c
index 217baa956..dcd4efb3b 100644
--- a/Xi/exevents.c
+++ b/Xi/exevents.c
@@ -619,8 +619,10 @@ DeepCopyPointerClasses(DeviceIntPtr from, DeviceIntPtr to)
             memcpy(to->button->xkb_acts, from->button->xkb_acts,
                    sizeof(XkbAction));
         }
-        else
+        else {
             free(to->button->xkb_acts);
+            to->button->xkb_acts = NULL;
+        }
 
         memcpy(to->button->labels, from->button->labels,
                from->button->numButtons * sizeof(Atom));