diff --git a/src/cmd/compile/doc.go b/src/cmd/compile/doc.go
index 46d4722086..b68ef274f3 100644
--- a/src/cmd/compile/doc.go
+++ b/src/cmd/compile/doc.go
@@ -83,7 +83,8 @@ Flags:
 		Without this flag, the -o output is a combination of both
 		linker and compiler input.
 	-m
-		Print optimization decisions.
+		Print optimization decisions. Higher values or repetition
+		produce more detail.
 	-memprofile file
 		Write memory profile for the compilation to file.
 	-memprofilerate rate