diff --git a/builtin/commit.c b/builtin/commit.c
index 6515da2786..95eeab1d51 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -184,6 +184,9 @@ static int list_paths(struct string_list *list, const char *with_tree,
 	int i;
 	char *m;
 
+	if (!pattern)
+		return 0;
+
 	for (i = 0; pattern[i]; i++)
 		;
 	m = xcalloc(1, i);
@@ -345,7 +348,7 @@ static char *prepare_index(int argc, const char **argv, const char *prefix,
 	 * and create commit from the_index.
 	 * We still need to refresh the index here.
 	 */
-	if (!pathspec || !*pathspec) {
+	if (!only && (!pathspec || !*pathspec)) {
 		fd = hold_locked_index(&index_lock, 1);
 		refresh_cache_or_die(refresh_flags);
 		if (active_cache_changed) {
diff --git a/t/t7501-commit.sh b/t/t7501-commit.sh
index 0f83be80ef..195e7477d8 100755
--- a/t/t7501-commit.sh
+++ b/t/t7501-commit.sh
@@ -108,6 +108,16 @@ test_expect_success 'amend commit' '
 	EDITOR=./editor git commit --amend
 '
 
+test_expect_success 'amend --only ignores staged contents' '
+	cp file file.expect &&
+	echo changed >file &&
+	git add file &&
+	git commit --no-edit --amend --only &&
+	git cat-file blob HEAD:file >file.actual &&
+	test_cmp file.expect file.actual &&
+	git diff --exit-code
+'
+
 test_expect_success 'set up editor' '
 	cat >editor <<-\EOF &&
 	#!/bin/sh