diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 430619a..7d7cbff 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1423,6 +1423,15 @@
 	u8 flags;
 } __packed;
 
+struct ictimesync_ref_data {
+	u64 parenttime;
+	u64 vmreferencetime;
+	u8 flags;
+	char leapflags;
+	char stratum;
+	u8 reserved[3];
+} __packed;
+
 struct hyperv_service_callback {
 	u8 msg_type;
 	char *log_msg;