diff --git a/README b/README
index c559810..dd3bab1 100644
--- a/README
+++ b/README
@@ -126,6 +126,7 @@
 	parse		Dump info related to option matching and parsing
 	diskutil	Dump info related to disk utilization updates
 	job:x		Dump info only related to job number x
+	mutex		Dump info only related to mutex up/down ops
 	? or help	Show available debug options.
 
 You can specify as many as you want, eg --debug=file,mem will enable