diff --git a/pkgs/development/compilers/swift/foundation/default.nix b/pkgs/development/compilers/swift/foundation/default.nix
index 409067db2ef7..efb35bd74c9f 100644
--- a/pkgs/development/compilers/swift/foundation/default.nix
+++ b/pkgs/development/compilers/swift/foundation/default.nix
@@ -1,3 +1,8 @@
+# TODO: We already package the CoreFoundation component of Foundation in:
+#   pkgs/os-specific/darwin/swift-corelibs/corefoundation.nix
+# This is separate because the CF build is completely different and part of
+# stdenv. Merging the two was kept outside of the scope of Swift work.
+
 { lib
 , stdenv
 , callPackage