diff --git a/source/blender/nodes/intern/node_common.cc b/source/blender/nodes/intern/node_common.cc
index 26131c626bd..7559198286f 100644
--- a/source/blender/nodes/intern/node_common.cc
+++ b/source/blender/nodes/intern/node_common.cc
@@ -302,6 +302,7 @@ static SocketDeclarationPtr declaration_for_interface_socket(
     case SOCK_CUSTOM:
       auto value = std::make_unique<decl::Custom>();
       value->init_socket_fn = get_init_socket_fn(ntree.tree_interface, io_socket);
+      value->idname_ = io_socket.socket_type;
       dst = std::move(value);
       break;
   }