diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fcf179df..10e37f50 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -46,7 +46,7 @@ jobs:
           -DBOOST_ROOT=boost_${BOOST_VERSION} \
           -DCMAKE_BUILD_TYPE=Release \
           -DCMAKE_CXX_COMPILER_LAUNCHER=ccache \
-          -DCMAKE_CXX_FLAGS="${CMAKE_CXX_FLAGS}"
+          -DCMAKE_CXX_FLAGS="-DCMAKE_CXX_FLAGS=-DJSON_HAS_CPP_14"
     - name: build
       run: cmake --build build --parallel 3
 
@@ -91,7 +91,7 @@ jobs:
           -DBOOST_ROOT=boost_${BOOST_VERSION} \
           -DCMAKE_BUILD_TYPE=Release \
           -DCMAKE_CXX_COMPILER_LAUNCHER=ccache \
-          -DCMAKE_CXX_FLAGS="${CMAKE_CXX_FLAGS}"
+          -DCMAKE_CXX_FLAGS="-I/usr/local/include -DCMAKE_CXX_FLAGS=-DJSON_HAS_CPP_14 -Wno-deprecated-declarations"
     - name: build
       run: cmake --build build --parallel 3 --verbose