1 files changed, 1 insertions, 1 deletions
diff --git a/common.mk b/common.mk
index d4dc2572d0..e16c72b78d 100644
--- a/common.mk
+++ b/common.mk
@@ -1071,7 +1071,7 @@ help: PHONY
 	"  gdb-ruby:        runs test.rb by ruby under gdb" \
 	"  check:           equals make test test-all" \
 	"  test:            ruby core tests" \
-	"  test-all:        all ruby tests" \
+	"  test-all:        all ruby tests [TEST=<specific_test_file.rb>]" \
 	"  test-rubyspec:   run RubySpec test suite" \
 	"  update-rubyspec: update local copy of RubySpec" \
 	"  benchmark:       benchmark this ruby and COMPARE_RUBY" \