diff --git a/CMakeLists.txt b/CMakeLists.txt
index 338cecc..edfd6a0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,13 +2,6 @@ cmake_minimum_required(VERSION 3.28)
 
 project(tsb_libavr LANGUAGES CXX)
 
-# CMake's GNU compiler module appends "-O3 -DNDEBUG" to CMAKE_CXX_FLAGS_RELEASE
-# after the libavr toolchain sets "-Os", and the later -O3 wins — so a Release
-# build is silently -O3, ~15-20 % larger than -Os. For a boot loader measured to
-# the byte that is fatal, so strip it and get the size build the design intends.
-# (The same leak affects libavr's own Release builds; a fix belongs upstream.)
-string(REPLACE "-O3" "" CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE}")
-
 # libavr from a local checkout (LIBAVR_ROOT) or the forge; the toolchain file
 # comes from the same checkout via CMakePresets.json.
 include(FetchContent)