diff --git a/.github/workflows/test-osx.yml b/.github/workflows/test-osx.yml
index bf2008d4..2521c09a 100644
--- a/.github/workflows/test-osx.yml
+++ b/.github/workflows/test-osx.yml
@@ -36,6 +36,7 @@ jobs:
           --builddir=build \
           cxx.name=${{ matrix.cxx }} \
           cxxflags=-std=${{ matrix.std }} \
+          cppflags=-std=${{ matrix.std }} \
           -j`sysctl -n hw.ncpu`
     - name: test
       run: |
@@ -44,5 +45,6 @@ jobs:
           --builddir=build\
           cxx.name=${{ matrix.cxx }} \
           cxxflags=-std=${{ matrix.std }} \
+          cppflags=-std=${{ matrix.std }} \
           -j`sysctl -n hw.ncpu` \
           test.report
diff --git a/.github/workflows/test-ubuntu.yml b/.github/workflows/test-ubuntu.yml
index 9910232e..74718b68 100644
--- a/.github/workflows/test-ubuntu.yml
+++ b/.github/workflows/test-ubuntu.yml
@@ -39,6 +39,7 @@ jobs:
           --builddir=build \
           cxx.name=${{ matrix.cxx }} \
           cxxflags=-std=${{ matrix.std }} \
+          cppflags=-std=${{ matrix.std }} \
           -j`nproc`
     - name: test
       run: |
@@ -47,5 +48,6 @@ jobs:
           --builddir=build \
           cxx.name=${{ matrix.cxx }} \
           cxxflags=-std=${{ matrix.std }} \
+          cppflags=-std=${{ matrix.std }} \
           -j`nproc` \
           test.report