diff --git a/src/libCom/timer/osiTimer.h b/src/libCom/timer/osiTimer.h
index bd1c3c33d..a517fbae5 100644
--- a/src/libCom/timer/osiTimer.h
+++ b/src/libCom/timer/osiTimer.h
@@ -61,6 +61,13 @@ public:
      */
     epicsShareFunc osiTimer ( double delay, osiTimerQueue & queueIn );
     epicsShareFunc osiTimer ( double delay);
+
+    /*
+     * Create an inactive timer
+     *
+     * ** Warning ** default timer queue has no manager thread and is typically
+     * processed by the file descriptor manager
+     */
     epicsShareFunc osiTimer ( osiTimerQueue & queueIn );
     epicsShareFunc osiTimer ();