diff --git a/refs.c b/refs.c
index 6b506aeea3..efa16b739d 100644
--- a/refs.c
+++ b/refs.c
@@ -1383,25 +1383,25 @@ static int transaction_refname_valid(const char *refname,
 	return 1;
 }
 
-int ref_transaction_update(struct ref_transaction *transaction,
-			   const char *refname,
-			   const struct object_id *new_oid,
-			   const struct object_id *old_oid,
-			   const char *new_target,
-			   const char *old_target,
-			   unsigned int flags, const char *msg,
-			   struct strbuf *err)
+enum ref_transaction_error ref_transaction_update(struct ref_transaction *transaction,
+						  const char *refname,
+						  const struct object_id *new_oid,
+						  const struct object_id *old_oid,
+						  const char *new_target,
+						  const char *old_target,
+						  unsigned int flags, const char *msg,
+						  struct strbuf *err)
 {
 	assert(err);
 
 	if ((flags & REF_FORCE_CREATE_REFLOG) &&
 	    (flags & REF_SKIP_CREATE_REFLOG)) {
 		strbuf_addstr(err, _("refusing to force and skip creation of reflog"));
-		return -1;
+		return REF_TRANSACTION_ERROR_GENERIC;
 	}
 
 	if (!transaction_refname_valid(refname, new_oid, flags, err))
-		return -1;
+		return REF_TRANSACTION_ERROR_GENERIC;
 
 	if (flags & ~REF_TRANSACTION_UPDATE_ALLOWED_FLAGS)
 		BUG("illegal flags 0x%x passed to ref_transaction_update()", flags);
diff --git a/refs.h b/refs.h
index d65de6ab5f..71d5c186d0 100644
--- a/refs.h
+++ b/refs.h
@@ -905,14 +905,14 @@ struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
  * See the above comment "Reference transaction updates" for more
  * information.
  */
-int ref_transaction_update(struct ref_transaction *transaction,
-			   const char *refname,
-			   const struct object_id *new_oid,
-			   const struct object_id *old_oid,
-			   const char *new_target,
-			   const char *old_target,
-			   unsigned int flags, const char *msg,
-			   struct strbuf *err);
+enum ref_transaction_error ref_transaction_update(struct ref_transaction *transaction,
+						  const char *refname,
+						  const struct object_id *new_oid,
+						  const struct object_id *old_oid,
+						  const char *new_target,
+						  const char *old_target,
+						  unsigned int flags, const char *msg,
+						  struct strbuf *err);
 
 /*
  * Similar to `ref_transaction_update`, but this function is only for adding