diff --git a/.gitlab-ci/windows/mesa_deps_build.ps1 b/.gitlab-ci/windows/mesa_deps_build.ps1
index b960fae3c57..70ed7395c26 100644
--- a/.gitlab-ci/windows/mesa_deps_build.ps1
+++ b/.gitlab-ci/windows/mesa_deps_build.ps1
@@ -82,6 +82,7 @@ cmake ../llvm `
 -DCMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded `
 -DCMAKE_PREFIX_PATH="$depsInstallPath" `
 -DCMAKE_INSTALL_PREFIX="$depsInstallPath" `
+-DCMAKE_CXX_FLAGS="/utf-8" `
 -DLLVM_ENABLE_PROJECTS="clang" `
 -DLLVM_TARGETS_TO_BUILD="AMDGPU;X86" `
 -DLLVM_OPTIMIZED_TABLEGEN=TRUE `