diff --git a/Documentation/diff-format.txt b/Documentation/diff-format.txt
index 1a99e85ee5..9e64539975 100644
--- a/Documentation/diff-format.txt
+++ b/Documentation/diff-format.txt
@@ -45,7 +45,7 @@ with a '-p' option, they do not produce the output described above
 instead they produce a patch file.
 
 The patch generation can be customized at two levels.  This
-customization also applies to "git-diff-tree-helper".
+customization also applies to "git-diff-helper".
 
 1. When the environment variable 'GIT_EXTERNAL_DIFF' is not set,
    these commands internally invoke "diff" like this:
diff --git a/Documentation/git-diff-tree-helper.txt b/Documentation/git-diff-helper.txt
similarity index 100%
rename from Documentation/git-diff-tree-helper.txt
rename to Documentation/git-diff-helper.txt
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 98d923db92..134afffe3f 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -149,7 +149,7 @@ link:git-rpull.html[git-rpull]::
 
 Interogators:
 
-link:git-diff-tree-helper.html[git-diff-tree-helper]::
+link:git-diff-helper.html[git-diff-helper]::
 	Generates patch format output for git-diff-*
 
 link:git-rpush.html[git-rpush]::
diff --git a/Makefile b/Makefile
index 92b7cdf766..23129c4421 100644
--- a/Makefile
+++ b/Makefile
@@ -27,7 +27,7 @@ PROG=   git-update-cache git-diff-files git-init-db git-write-tree \
 	git-check-files git-ls-tree git-merge-base git-merge-cache \
 	git-unpack-file git-export git-diff-cache git-convert-cache \
 	git-http-pull git-rpush git-rpull git-rev-list git-mktag \
-	git-diff-tree-helper git-tar-tree git-local-pull git-write-blob \
+	git-diff-helper git-tar-tree git-local-pull git-write-blob \
 	git-get-tar-commit-id
 
 all: $(PROG)
@@ -101,7 +101,7 @@ git-rpush: rsh.c
 git-rpull: rsh.c pull.c
 git-rev-list: rev-list.c
 git-mktag: mktag.c
-git-diff-tree-helper: diff-tree-helper.c
+git-diff-helper: diff-helper.c
 git-tar-tree: tar-tree.c
 git-write-blob: write-blob.c
 
diff --git a/diff-tree-helper.c b/diff-helper.c
similarity index 100%
rename from diff-tree-helper.c
rename to diff-helper.c
diff --git a/diff.h b/diff.h
index 0b76cc4281..c146d8acf8 100644
--- a/diff.h
+++ b/diff.h
@@ -17,7 +17,7 @@ extern void diff_change(unsigned mode1, unsigned mode2,
 
 extern void diff_unmerge(const char *path);
 
-/* These are for diff-tree-helper */
+/* These are for diff-helper */
 
 struct diff_spec {
 	unsigned char blob_sha1[20];