diff --git a/builtin-commit.c b/builtin-commit.c
index 518ebe0347..61770ef456 100644
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -662,6 +662,7 @@ static void print_summary(const char *prefix, const unsigned char *sha1)
 	rev.show_root_diff = 1;
 	rev.commit_format = get_commit_format("format:%h: %s");
 	rev.always_show_header = 0;
+	diff_setup_done(&rev.diffopt);
 
 	printf("Created %scommit ", initial_commit ? "initial " : "");