diff --git a/src/libboard_artiq/src/cxp_downconn.rs b/src/libboard_artiq/src/cxp_downconn.rs
index 7b982ad..a189d4f 100644
--- a/src/libboard_artiq/src/cxp_downconn.rs
+++ b/src/libboard_artiq/src/cxp_downconn.rs
@@ -50,7 +50,7 @@ pub fn loopback_testing(channel: usize, timer: &mut GlobalTimer, speed: CXP_SPEE
         data_slice[..4].clone_from_slice(&data.to_be_bytes());
         cxp_proto::downconn_debug_send(
             channel,
-            &cxp_proto::Packet::CtrlAckLoopback {
+            &cxp_proto::UpConnPacket::CtrlAckLoopback {
                 ackcode: 0x00,
                 length: 0x04,
                 data: data_slice,