diff --git a/.gitlab-ci/ci-cmake-build.sh b/.gitlab-ci/ci-cmake-build.sh
index b56b2e74a..eab55d181 100755
--- a/.gitlab-ci/ci-cmake-build.sh
+++ b/.gitlab-ci/ci-cmake-build.sh
@@ -1,10 +1,10 @@
 #!/usr/bin/env bash
 # SPDX-License-Identifier: CC0-1.0
-# SPDX-FileCopyrightText: 2018-2022 Collabora, Ltd. and the Monado contributors
+# SPDX-FileCopyrightText: 2018-2026 Collabora, Ltd. and the Monado contributors
 set -e
 set -x
 
 rm -rf build
-cmake -GNinja -B build -S . "$@"
+cmake -GNinja -B build -S . -DCMAKE_COMPILE_WARNING_AS_ERROR=ON "$@"
 echo "Build Options:"; grep "^XRT_" build/CMakeCache.txt
 ninja -C build
diff --git a/.gitlab-ci/windows/monado_build.ps1 b/.gitlab-ci/windows/monado_build.ps1
index 8751ef203..6a0e0dcb6 100644
--- a/.gitlab-ci/windows/monado_build.ps1
+++ b/.gitlab-ci/windows/monado_build.ps1
@@ -1,5 +1,5 @@
 # Copyright 2019-2022, Mesa contributors
-# Copyright 2022, Collabora, Ltd.
+# Copyright 2022-2026, Collabora, Ltd.
 # SPDX-License-Identifier: MIT
 # Based on https://gitlab.freedesktop.org/mesa/mesa/-/blob/8396df5ad90aeb6ab2267811aba2187954562f81/.gitlab-ci/windows/mesa_build.ps1
 
@@ -66,6 +66,7 @@ $cmakeArgs = @(
     "-DCMAKE_BUILD_TYPE=RelWithDebInfo"
     "-DCMAKE_TOOLCHAIN_FILE=$toolchainfile"
     "-DCMAKE_INSTALL_PREFIX=$installdir"
+    "-DCMAKE_COMPILE_WARNING_AS_ERROR=ON"
     "-DX_VCPKG_APPLOCAL_DEPS_INSTALL=ON"
 )
 cmake @cmakeArgs