diff --git a/Xi/exevents.c b/Xi/exevents.c
index 622e8cc33..719e9db0d 100644
--- a/Xi/exevents.c
+++ b/Xi/exevents.c
@@ -1169,6 +1169,7 @@ CheckDeviceGrabAndHintWindow(WindowPtr pWin, int type,
 	tempGrab.pointerMode = GrabModeAsync;
 	tempGrab.confineTo = NullWindow;
 	tempGrab.cursor = NullCursor;
+        tempGrab.genericMasks = NULL;
 	(*dev->deviceGrab.ActivateGrab) (dev, &tempGrab, currentTime, TRUE);
     }
 }
diff --git a/dix/events.c b/dix/events.c
index 58d9ed43a..51bd2d8d2 100644
--- a/dix/events.c
+++ b/dix/events.c
@@ -5912,6 +5912,7 @@ ExtGrabDevice(ClientPtr client,
             last->next = xcalloc(1, sizeof(GenericMaskRec));
             last = last->next;
             *last = *ge_masks;
+            last->next = NULL;
             ge_masks = ge_masks->next;
         }
     }