diff --git a/.github/workflows/c-cpp.yml b/.github/workflows/c-cpp.yml
index 36e4c14bf..ca47ff6ee 100644
--- a/.github/workflows/c-cpp.yml
+++ b/.github/workflows/c-cpp.yml
@@ -12,7 +12,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-16_04, ubuntu-18_04, ubuntu-20.04, macos-10.15, macos-11.0]
+        os: [ubuntu-16.04, ubuntu-18.04, ubuntu-20.04, macos-10.15, macos-11.0]
         configs: [default, pam]
         # Then we include any extra configs we want to test for specific VMs.
         include:
@@ -26,7 +26,7 @@ jobs:
           - { os: ubuntu-18.04, configs: selinux }
           - { os: ubuntu-18.04, configs: kitchensink }
           - { os: ubuntu-18.04, configs: without-openssl }
-          - { os: ubuntu-16_04, configs: kitchensink }
+          - { os: ubuntu-16.04, configs: kitchensink }
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2