diff --git a/diff.c b/diff.c
index 006aa017e2..11798af0c1 100644
--- a/diff.c
+++ b/diff.c
@@ -1948,17 +1948,23 @@ void diff_free_filespec_data(struct diff_filespec *s)
 	s->cnt_data = NULL;
 }
 
-static void prep_temp_blob(struct diff_tempfile *temp,
+static void prep_temp_blob(const char *path, struct diff_tempfile *temp,
 			   void *blob,
 			   unsigned long size,
 			   const unsigned char *sha1,
 			   int mode)
 {
 	int fd;
+	struct strbuf buf = STRBUF_INIT;
 
 	fd = git_mkstemp(temp->tmp_path, PATH_MAX, ".diff_XXXXXX");
 	if (fd < 0)
 		die("unable to create temp-file: %s", strerror(errno));
+	if (convert_to_working_tree(path,
+			(const char *)blob, (size_t)size, &buf)) {
+		blob = buf.buf;
+		size = buf.len;
+	}
 	if (write_in_full(fd, blob, size) != size)
 		die("unable to write temp-file");
 	close(fd);
@@ -1966,6 +1972,7 @@ static void prep_temp_blob(struct diff_tempfile *temp,
 	strcpy(temp->hex, sha1_to_hex(sha1));
 	temp->hex[40] = 0;
 	sprintf(temp->mode, "%06o", mode);
+	strbuf_release(&buf);
 }
 
 static struct diff_tempfile *prepare_temp_file(const char *name,
@@ -2006,7 +2013,7 @@ static struct diff_tempfile *prepare_temp_file(const char *name,
 				die("readlink(%s)", name);
 			if (ret == sizeof(buf))
 				die("symlink too long: %s", name);
-			prep_temp_blob(temp, buf, ret,
+			prep_temp_blob(name, temp, buf, ret,
 				       (one->sha1_valid ?
 					one->sha1 : null_sha1),
 				       (one->sha1_valid ?
@@ -2032,7 +2039,7 @@ static struct diff_tempfile *prepare_temp_file(const char *name,
 	else {
 		if (diff_populate_filespec(one, 0))
 			die("cannot read data blob for %s", one->path);
-		prep_temp_blob(temp, one->data, one->size,
+		prep_temp_blob(name, temp, one->data, one->size,
 			       one->sha1, one->mode);
 	}
 	return temp;
diff --git a/t/t4020-diff-external.sh b/t/t4020-diff-external.sh
index 281680d95a..f8c99f1a98 100755
--- a/t/t4020-diff-external.sh
+++ b/t/t4020-diff-external.sh
@@ -136,4 +136,20 @@ test_expect_success 'GIT_EXTERNAL_DIFF with more than one changed files' '
 	GIT_EXTERNAL_DIFF=echo git diff
 '
 
+echo "#!$SHELL_PATH" >fake-diff.sh
+cat >> fake-diff.sh <<\EOF
+cat $2 >> crlfed.txt
+EOF
+chmod a+x fake-diff.sh
+
+keep_only_cr () {
+	tr -dc '\015'
+}
+
+test_expect_success 'external diff with autocrlf = true' '
+	git config core.autocrlf true &&
+	GIT_EXTERNAL_DIFF=./fake-diff.sh git diff &&
+	test $(wc -l < crlfed.txt) = $(cat crlfed.txt | keep_only_cr | wc -c)
+'
+
 test_done