diff --git a/pkgs/os-specific/darwin/apple-sdk/default.nix b/pkgs/os-specific/darwin/apple-sdk/default.nix
index dbfd3b05fa5..97523cf15a8 100644
--- a/pkgs/os-specific/darwin/apple-sdk/default.nix
+++ b/pkgs/os-specific/darwin/apple-sdk/default.nix
@@ -108,6 +108,7 @@ let
 
         local tbd_source=${darwin-stubs}/System/Library/Frameworks/$nested_path/Versions/$current
         if [ "${name}" != "Kernel" ]; then
+          # The Kernel.framework has headers but no actual library component.
           cp -v $tbd_source/*.tbd .
         fi