diff --git a/dix/devices.c b/dix/devices.c
index 839de35aa..207b78b87 100644
--- a/dix/devices.c
+++ b/dix/devices.c
@@ -1890,6 +1890,7 @@ ProcGetPointerMapping(ClientPtr client)
      * the ClientPointer could change. */
     DeviceIntPtr ptr = PickPointer(client);
     ButtonClassPtr butc = ptr->button;
+    int nElts;
     int rc;
 
     REQUEST_SIZE_MATCH(xReq);
@@ -1898,15 +1899,16 @@ ProcGetPointerMapping(ClientPtr client)
     if (rc != Success)
         return rc;
 
+    nElts = (butc) ? butc->numButtons : 0;
     rep = (xGetPointerMappingReply) {
         .type = X_Reply,
-        .nElts = (butc) ? butc->numButtons : 0,
+        .nElts = nElts,
         .sequenceNumber = client->sequence,
-        .length = ((unsigned) rep.nElts + (4 - 1)) / 4
+        .length = ((unsigned) nElts + (4 - 1)) / 4
     };
     WriteReplyToClient(client, sizeof(xGetPointerMappingReply), &rep);
     if (butc)
-        WriteToClient(client, (int) rep.nElts, &butc->map[1]);
+        WriteToClient(client, nElts, &butc->map[1]);
     return Success;
 }