diff --git a/builtin/commit.c b/builtin/commit.c
index b3bd2d4..109742e 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -186,6 +186,7 @@
 	gitmodules_config();
 	git_config(fn, s);
 	determine_whence(s);
+	init_diff_ui_defaults();
 	s->hints = advice_status_hints; /* must come after git_config() */
 }