diff --git a/git-latexdiff b/git-latexdiff
index 2deadaf..87c7971 100755
--- a/git-latexdiff
+++ b/git-latexdiff
@@ -38,9 +38,11 @@ git_latexdiff_version=1.0
 usage () {
             cat << EOF
 Usage: $(basename $0) [options] OLD [NEW]
+       $(basename $0) [options] OLD --
 Call latexdiff on two Git revisions of a file.
 
 OLD and NEW are Git revision identifiers. NEW defaults to HEAD.
+If "--" is used for NEW, then diff against the working directory.
 
 Options:
     --help                this help message
@@ -261,7 +263,8 @@ verbose_progress
 cd ../new || die "Cannot cd to new/"
 ln -s -t . "$initial_dir"/*
 if test "$new" != "--"; then
-    # if new == "--" then diff working dir
+    # if new == "--" then diff working dir (already there thanks to ln
+    # -s above).
     git --git-dir="$git_dir" --work-tree=. checkout "$new" -- . || die "checkout failed for new/"
 fi
 verbose_progress