diff --git a/.github/workflows/build-linux.yml b/.github/workflows/build-linux.yml
index 2195ad05c..7aa818d04 100644
--- a/.github/workflows/build-linux.yml
+++ b/.github/workflows/build-linux.yml
@@ -50,6 +50,7 @@ jobs:
         run: |
           # LLVM (clang) 9 is not in Bionic's repositories so we add the official LLVM repository.
           if [ "${{ matrix.compiler }}" = "clang" ] && [ "${{ matrix.version }}" = "9" ]; then
+            # pool.sks-keyservers.net is the SKS GPG global keyserver pool
             # 15CF4D18AF4F7421 is the GPG key for the LLVM apt repository
             gpg --keyserver pool.sks-keyservers.net --recv-key 15CF4D18AF4F7421
             gpg -a --export 15CF4D18AF4F7421 | sudo apt-key add -
diff --git a/.github/workflows/build-python.yml b/.github/workflows/build-python.yml
index e348e3125..5b9f7418b 100644
--- a/.github/workflows/build-python.yml
+++ b/.github/workflows/build-python.yml
@@ -63,6 +63,7 @@ jobs:
         run: |
           # LLVM (clang) 9 is not in Bionic's repositories so we add the official LLVM repository.
           if [ "${{ matrix.compiler }}" = "clang" ] && [ "${{ matrix.version }}" = "9" ]; then
+            # pool.sks-keyservers.net is the SKS GPG global keyserver pool
             # 15CF4D18AF4F7421 is the GPG key for the LLVM apt repository
             gpg --keyserver pool.sks-keyservers.net --recv-key 15CF4D18AF4F7421
             gpg -a --export 15CF4D18AF4F7421 | sudo apt-key add -