diff --git a/mailmap.c b/mailmap.c
index badf6a4dad..8b6dc36bbc 100644
--- a/mailmap.c
+++ b/mailmap.c
@@ -69,7 +69,7 @@ static void add_mapping(struct string_list *map,
 		index = -1 - index;
 	} else {
 		/* create mailmap entry */
-		struct string_list_item *item = string_list_insert_at_index(index, old_email, map);
+		struct string_list_item *item = string_list_insert_at_index(map, index, old_email);
 		item->util = xmalloc(sizeof(struct mailmap_entry));
 		memset(item->util, 0, sizeof(struct mailmap_entry));
 		((struct mailmap_entry *)item->util)->namemap.strdup_strings = 1;
diff --git a/string-list.c b/string-list.c
index de89efd2d8..84444c2c19 100644
--- a/string-list.c
+++ b/string-list.c
@@ -53,11 +53,11 @@ static int add_entry(int insert_at, struct string_list *list, const char *string
 
 struct string_list_item *string_list_insert(struct string_list *list, const char *string)
 {
-	return string_list_insert_at_index(-1, string, list);
+	return string_list_insert_at_index(list, -1, string);
 }
 
-struct string_list_item *string_list_insert_at_index(int insert_at,
-						     const char *string, struct string_list *list)
+struct string_list_item *string_list_insert_at_index(struct string_list *list,
+						     int insert_at, const char *string)
 {
 	int index = add_entry(insert_at, list, string);
 
diff --git a/string-list.h b/string-list.h
index 3d5a8de4b5..a4e1919ada 100644
--- a/string-list.h
+++ b/string-list.h
@@ -30,8 +30,8 @@ int string_list_has_string(const struct string_list *list, const char *string);
 int string_list_find_insert_index(const struct string_list *list, const char *string,
 				  int negative_existing_index);
 struct string_list_item *string_list_insert(struct string_list *list, const char *string);
-struct string_list_item *string_list_insert_at_index(int insert_at,
-						     const char *string, struct string_list *list);
+struct string_list_item *string_list_insert_at_index(struct string_list *list,
+						     int insert_at, const char *string);
 struct string_list_item *string_list_lookup(const char *string, struct string_list *list);
 
 /* Use these functions only on unsorted lists: */