diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9222204..60b3860 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,10 +10,10 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         toolchain:
-          - {compiler: gcc, version: 13, flags: ['-cpp -O3 -march=native -flto']}
-          - {compiler: intel, version: '2023.2', flags: ['-fpp -O3 -xhost -ipo']}
-          - {compiler: intel-classic, version: '2021.10', flags: ['-fpp -O3 -xhost -ipo']}
-          - {compiler: nvidia-hpc, version: '23.11', flags: ['-Mpreprocess -Ofast -Minline']}
+          - {compiler: gcc, version: 13, flags: ['-cpp -O3 -march=native']}
+          - {compiler: intel, version: '2023.2', flags: ['-fpp -O3 -xhost']}
+          - {compiler: intel-classic, version: '2021.10', flags: ['-fpp -O3 -xhost']}
+          - {compiler: nvidia-hpc, version: '23.11', flags: ['-Mpreprocess -Ofast']}
         include:
           - os: ubuntu-latest
             toolchain: {compiler: gcc, version: 12, flags: ['-cpp -O3 -march=native']}
@@ -41,6 +41,6 @@ jobs:
           github-token: ${{ secrets.GITHUB_TOKEN }}
 
       - run: |
-          fpm test --compiler ${{ env.FC }} --flag "${{ join(matrix.toolchain.flags, ' ') }}"
+          fpm test --compiler ${{ env.FC }} --c-compiler ${{ env.CC }} --cxx-compiler ${{ env.CXX }} --flag "${{ join(matrix.toolchain.flags, ' ') }}"
     #      ${{ env.FC }} ... # environment vars FC, CC, and CXX are set
     #      ${{ steps.setup-fortran.outputs.fc }} ... # outputs work too