diff --git a/sha1_name.c b/sha1_name.c
index 3820f28ae..01e49a92d 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -464,7 +464,7 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 		struct strbuf buf = STRBUF_INIT;
 		int ret;
 		/* try the @{-N} syntax for n-th checkout */
-		ret = interpret_branch_name(str+at, &buf);
+		ret = interpret_branch_name(str, &buf);
 		if (ret > 0) {
 			/* substitute this branch name and restart */
 			return get_sha1_1(buf.buf, buf.len, sha1, 0);