diff --git a/.github/workflows/c-cpp.yml b/.github/workflows/c-cpp.yml
index 424c193fb..b5b6de7fa 100644
--- a/.github/workflows/c-cpp.yml
+++ b/.github/workflows/c-cpp.yml
@@ -111,6 +111,12 @@ jobs:
           - { target: macos-15, config: pam }
     runs-on: ${{ matrix.target }}
     steps:
+    - name: check RUN_ONLY_TEST
+      # For testing, you can set the repo variable RUN_ONLY_TEST in your repo
+      # (Repo -> Settings -> Security -> Actions -> Variables) to run only
+      # that test config.
+      if: vars.RUN_ONLY_TEST != ''
+      run: sh -c 'if [ "${{ vars.RUN_ONLY_TEST }}" != "${{ matrix.target }} ${{matrix.config }}" ]; then exit 1; else exit 0; fi'
     - name: set cygwin git params
       if: ${{ startsWith(matrix.target, 'windows') }}
       run: git config --global core.autocrlf input