diff --git a/include/asterisk/pbx.h b/include/asterisk/pbx.h
index 7ada1532f8..0018263807 100644
--- a/include/asterisk/pbx.h
+++ b/include/asterisk/pbx.h
@@ -492,6 +492,10 @@ int ast_extension_close(const char *pattern, const char *data, int needmore);
  *
  * This adds a new extension to the asterisk extension list.
  *
+ * \note It is possible for autoservice to be started and stopped on c during this
+ * function call, it is important that c is not locked prior to calling this. Otherwise
+ * a deadlock may occur
+ *
  * \retval 0 on success 
  * \retval -1 on failure.
  */