diff --git a/src/bacnet/basic/object/bacfile.c b/src/bacnet/basic/object/bacfile.c
index e34da9dc..aac63f2e 100644
--- a/src/bacnet/basic/object/bacfile.c
+++ b/src/bacnet/basic/object/bacfile.c
@@ -393,7 +393,7 @@ uint32_t bacfile_instance_from_tsm(uint8_t invokeID)
     if (found) {
         if (!npdu_data.network_layer_message &&
             npdu_data.data_expecting_reply &&
-            (apdu[0] == PDU_TYPE_CONFIRMED_SERVICE_REQUEST)) {
+            ((apdu[0] & 0xF0) == PDU_TYPE_CONFIRMED_SERVICE_REQUEST)) {
             len = apdu_decode_confirmed_service_request(&apdu[0], apdu_len,
                 &service_data, &service_choice, &service_request,
                 &service_request_len);