diff --git a/include/asterisk.h b/include/asterisk.h
index e33be868f3e5776878735366d8c1fe79e22d442d..8c748d99e250f9c58aa15207716e258599cfd3b1 100755
--- a/include/asterisk.h
+++ b/include/asterisk.h
@@ -91,6 +91,11 @@ void ast_unregister_file_version(const char *file);
  * \code
  * ASTERISK_FILE_VERSION(__FILE__, "\$Revision\$")
  * \endcode
+ *
+ * \note The dollar signs above have been protected with backslashes to keep
+ * CVS from modifying them in this file; under normal circumstances they would
+ * not be present and CVS would expand the Revision keyword into the file's
+ * revision number.
  */
 #ifdef __GNUC__
 #define ASTERISK_FILE_VERSION(file, version) \