diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 4cb7e9a..7382364 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -427,7 +427,7 @@ jobs:
             -DLIBCXXABI_USE_COMPILER_RT=YES `
             -DLIBUNWIND_USE_COMPILER_RT=YES `
             -DLIBCXXABI_USE_LLVM_UNWINDER=YES `
-            -DLIBCXX_EXTRA_SITE_DEFINES="__USE_MINGW_ANSI_STDIO=1" `
+            -DLIBCXX_EXTRA_SITE_DEFINES="__USE_MINGW_ANSI_STDIO=${{startsWith(matrix.arch, 'a') && '0' || '1'}}" `
             -DCMAKE_INSTALL_MESSAGE=NEVER `
             -DLLVM_LIT_ARGS="-v --time-tests"
           ninja
diff --git a/.github/workflows/test-libcxx.yml b/.github/workflows/test-libcxx.yml
index 3d33151..7f54c20 100644
--- a/.github/workflows/test-libcxx.yml
+++ b/.github/workflows/test-libcxx.yml
@@ -98,7 +98,7 @@ jobs:
             -DLIBCXXABI_USE_COMPILER_RT=YES `
             -DLIBUNWIND_USE_COMPILER_RT=YES `
             -DLIBCXXABI_USE_LLVM_UNWINDER=YES `
-            -DLIBCXX_EXTRA_SITE_DEFINES="__USE_MINGW_ANSI_STDIO=1" `
+            -DLIBCXX_EXTRA_SITE_DEFINES="__USE_MINGW_ANSI_STDIO=${{startsWith(matrix.arch, 'a') && '0' || '1'}}" `
             -DCMAKE_INSTALL_MESSAGE=NEVER `
             -DLLVM_LIT_ARGS="-v --time-tests"
           ninja