diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index 0bf5356..3738cf5 100644
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -4445,6 +4445,11 @@ pg_largeobject_aclcheck_snapshot(Oid lobj_oid, Oid roleid, AclMode mode,
 AclResult
 pg_namespace_aclcheck(Oid nsp_oid, Oid roleid, AclMode mode)
 {
+	if (mode == ACL_CREATE && !allowSystemTableMods &&
+		(IsSystemNamespace(nsp_oid) || IsToastNamespace(nsp_oid)) &&
+		IsNormalProcessingMode())
+		return ACLCHECK_NO_PRIV;
+
 	if (pg_namespace_aclmask(nsp_oid, roleid, mode, ACLMASK_ANY) != 0)
 		return ACLCHECK_OK;
 	else