diff --git a/refs.c b/refs.c
index a007cf325..9d9bbebfb 100644
--- a/refs.c
+++ b/refs.c
@@ -3637,9 +3637,10 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 
 	/* Copy, sort, and reject duplicate refs */
 	qsort(updates, n, sizeof(*updates), ref_update_compare);
-	ret = ref_update_reject_duplicates(updates, n, err);
-	if (ret)
+	if (ref_update_reject_duplicates(updates, n, err)) {
+		ret = TRANSACTION_GENERIC_ERROR;
 		goto cleanup;
+	}
 
 	/* Acquire all locks while verifying old values */
 	for (i = 0; i < n; i++) {
@@ -3653,10 +3654,12 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 						   update->flags,
 						   &update->type);
 		if (!update->lock) {
+			ret = (errno == ENOTDIR)
+				? TRANSACTION_NAME_CONFLICT
+				: TRANSACTION_GENERIC_ERROR;
 			if (err)
 				strbuf_addf(err, "Cannot lock the ref '%s'.",
 					    update->refname);
-			ret = 1;
 			goto cleanup;
 		}
 	}
@@ -3666,15 +3669,16 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 		struct ref_update *update = updates[i];
 
 		if (!is_null_sha1(update->new_sha1)) {
-			ret = write_ref_sha1(update->lock, update->new_sha1,
-					     update->msg);
-			update->lock = NULL; /* freed by write_ref_sha1 */
-			if (ret) {
+			if (write_ref_sha1(update->lock, update->new_sha1,
+					   update->msg)) {
+				update->lock = NULL; /* freed by write_ref_sha1 */
 				if (err)
 					strbuf_addf(err, "Cannot update the ref '%s'.",
 						    update->refname);
+				ret = TRANSACTION_GENERIC_ERROR;
 				goto cleanup;
 			}
+			update->lock = NULL; /* freed by write_ref_sha1 */
 		}
 	}
 
@@ -3683,14 +3687,16 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 		struct ref_update *update = updates[i];
 
 		if (update->lock) {
-			ret |= delete_ref_loose(update->lock, update->type,
-						err);
+			if (delete_ref_loose(update->lock, update->type, err))
+				ret = TRANSACTION_GENERIC_ERROR;
+
 			if (!(update->flags & REF_ISPRUNING))
 				delnames[delnum++] = update->lock->ref_name;
 		}
 	}
 
-	ret |= repack_without_refs(delnames, delnum, err);
+	if (repack_without_refs(delnames, delnum, err))
+		ret = TRANSACTION_GENERIC_ERROR;
 	for (i = 0; i < delnum; i++)
 		unlink_or_warn(git_path("logs/%s", delnames[i]));
 	clear_loose_ref_cache(&ref_cache);
diff --git a/refs.h b/refs.h
index 1a55cabb4..50b115acc 100644
--- a/refs.h
+++ b/refs.h
@@ -326,9 +326,14 @@ int ref_transaction_delete(struct ref_transaction *transaction,
 
 /*
  * Commit all of the changes that have been queued in transaction, as
- * atomically as possible.  Return a nonzero value if there is a
- * problem.
+ * atomically as possible.
+ *
+ * Returns 0 for success, or one of the below error codes for errors.
  */
+/* Naming conflict (for example, the ref names A and A/B conflict). */
+#define TRANSACTION_NAME_CONFLICT -1
+/* All other errors. */
+#define TRANSACTION_GENERIC_ERROR -2
 int ref_transaction_commit(struct ref_transaction *transaction,
 			   struct strbuf *err);