diff --git a/net/usrsock/usrsock_dev.c b/net/usrsock/usrsock_dev.c
index 252eab3c07..c3155754da 100644
--- a/net/usrsock/usrsock_dev.c
+++ b/net/usrsock/usrsock_dev.c
@@ -73,7 +73,7 @@ struct usrsockdev_s
     sem_t     sem;               /* Request semaphore (only one outstanding
                                   * request) */
     sem_t     acksem;            /* Request acknowledgment notification */
-    uint64_t  ackxid;            /* Exchange id for which waiting ack */
+    uint32_t  ackxid;            /* Exchange id for which waiting ack */
     uint16_t  nbusy;             /* Number of requests blocked from different
                                   * threads */
   } req;