diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 8e14948..b1d9ca9 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -9,8 +9,8 @@ jobs:
       fail-fast: false
       matrix:
         config:
-        - { os: macos-10.15 } # https://github.com/actions/virtual-environments/blob/main/images/macos/macos-10.15-Readme.md#xcode
-        - { os: macos-11.0  } # https://github.com/actions/virtual-environments/blob/main/images/macos/macos-11.0-Readme.md#xcode
+        - { os: macos-10.15 }
+        - { os: macos-11.0  }
         build: [Debug, Release]
 
     name: "${{matrix.config.os}}:${{matrix.build}}"
diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 6ff99f5..db09ac7 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -12,8 +12,9 @@ jobs:
         compiler:
         - { cc: "gcc-9",    cxx: "g++-9" }
         - { cc: "gcc-10",   cxx: "g++-10" }
-        - { cc: "clang-9",  cxx: "clang++-9" }
         - { cc: "clang-10", cxx: "clang++-10" }
+        - { cc: "clang-11", cxx: "clang++-11" }
+        - { cc: "clang-12", cxx: "clang++-12" }
 
     name: "${{matrix.compiler.cxx}}:${{matrix.build}}"
     steps: