diff --git a/include/ecrt.h b/include/ecrt.h
index 4b7d92bb0e50a4d8b4ff0f5bd8b6af2cbd12ae2a..e4e64ff2e3f586f305a1d331ee2067b865366ea2 100644
--- a/include/ecrt.h
+++ b/include/ecrt.h
@@ -90,6 +90,7 @@ typedef struct ec_slave ec_slave_t; /**< \see ec_slave */
 /*****************************************************************************/
 
 /** Bus status.
+ * This is used in ec_master_status_t.
  */
 typedef enum {
     EC_BUS_FAILURE = -1, /**< At least one slave with process data exchange