diff --git a/include/sound/sof/topology.h b/include/sound/sof/topology.h
index 796b6c8e851d..d12736e14b69 100644
--- a/include/sound/sof/topology.h
+++ b/include/sound/sof/topology.h
@@ -57,8 +57,8 @@ struct sof_ipc_comp {
 	uint32_t pipeline_id;
 	uint32_t core;
 
-	/* reserved for future use */
-	uint32_t reserved[1];
+	/* extended data length, 0 if no extended data */
+	uint32_t ext_data_length;
 } __packed;
 
 /*