diff --git a/Xi/exevents.c b/Xi/exevents.c
index d72f00ac2..8c8cdfdd4 100644
--- a/Xi/exevents.c
+++ b/Xi/exevents.c
@@ -338,6 +338,7 @@ DeepCopyDeviceClasses(DeviceIntPtr from, DeviceIntPtr to)
             FatalError("[Xi] no memory for class shift.\n");
         memcpy(v, from->valuator, sizeof(ValuatorClassRec));
         v->motion = NULL;
+        AllocateMotionHistory(to); /*XXX should be copied somehow */
 
         v->axes = (AxisInfoPtr)&v[1];
         memcpy(v->axes, from->valuator->axes, v->numAxes * sizeof(AxisInfo));