diff --git a/builtin/rebase.c b/builtin/rebase.c
index 28e7b7f..17450e9 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -270,15 +270,14 @@ static int edit_todo_file(unsigned flags)
 }
 
 static int get_revision_ranges(struct commit *upstream, struct commit *onto,
-			       struct object_id *orig_head, char *head_hash,
-			       char **revisions, char **shortrevisions)
+			       struct object_id *orig_head, char **revisions,
+			       char **shortrevisions)
 {
 	struct commit *base_rev = upstream ? upstream : onto;
 	const char *shorthead;
 
-	find_unique_abbrev_r(head_hash, orig_head, GIT_MAX_HEXSZ);
 	*revisions = xstrfmt("%s...%s", oid_to_hex(&base_rev->object.oid),
-						   head_hash);
+			     oid_to_hex(orig_head));
 
 	shorthead = find_unique_abbrev(orig_head, DEFAULT_ABBREV);
 
@@ -328,7 +327,6 @@ static void split_exec_commands(const char *cmd, struct string_list *commands)
 static int do_interactive_rebase(struct rebase_options *opts, unsigned flags)
 {
 	int ret;
-	char head_hash[GIT_MAX_HEXSZ];
 	char *revisions = NULL, *shortrevisions = NULL;
 	struct strvec make_script_args = STRVEC_INIT;
 	struct todo_list todo_list = TODO_LIST_INIT;
@@ -336,7 +334,7 @@ static int do_interactive_rebase(struct rebase_options *opts, unsigned flags)
 	struct string_list commands = STRING_LIST_INIT_DUP;
 
 	if (get_revision_ranges(opts->upstream, opts->onto, &opts->orig_head,
-				head_hash, &revisions, &shortrevisions))
+				&revisions, &shortrevisions))
 		return -1;
 
 	if (init_basic_state(&replay,