diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 79a611f..bfd0be4 100644
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -16,10 +16,20 @@
 	struct ref *ref;
 	struct object_id oid;
 
-	if (!get_oid_hex(name, &oid) && name[GIT_SHA1_HEXSZ] == ' ')
-		name += GIT_SHA1_HEXSZ + 1;
-	else
+	if (!get_oid_hex(name, &oid)) {
+		if (name[GIT_SHA1_HEXSZ] == ' ') {
+			/* <sha1> <ref>, find refname */
+			name += GIT_SHA1_HEXSZ + 1;
+		} else if (name[GIT_SHA1_HEXSZ] == '\0') {
+			; /* <sha1>, leave sha1 as name */
+		} else {
+			/* <ref>, clear cruft from oid */
+			oidclr(&oid);
+		}
+	} else {
+		/* <ref>, clear cruft from get_oid_hex */
 		oidclr(&oid);
+	}
 
 	ref = alloc_ref(name);
 	oidcpy(&ref->old_oid, &oid);