diff --git a/toolchain/xpcg/backend/c-mpc/backend.c b/toolchain/xpcg/backend/c-mpc/backend.c
index f8626f4..2064c0c 100644
--- a/toolchain/xpcg/backend/c-mpc/backend.c
+++ b/toolchain/xpcg/backend/c-mpc/backend.c
@@ -362,7 +362,7 @@ static int emit_interface_msg_function_send_impl(
 			break;
 		case TYPE_BUFFER:
 			emit(ctx,
-			     "msg_data.msg_request.%s_offset = offset;\n",
+			     "msg_data.msg_request.%s_offset = in_offset;\n",
 			     param->p_name);
 			emit(ctx,
 			     "msg_data.msg_request.%s_len = %s_len;\n",
@@ -693,7 +693,7 @@ static int emit_interface_dispatcher_impl_msg(
 			break;
 		case TYPE_BUFFER:
 			emit(ctx,
-			     "xpc_string_t %s = "
+			     "xpc_buffer_t %s = "
 			     "XPC_BUFFER_IN(msg, " MSG_STRUCT_NAME
 			     ".msg_request.%s_offset, " MSG_STRUCT_NAME
 			     ".msg_request.%s_len);\n",