diff --git a/pkgs/development/compilers/rust/rustc.nix b/pkgs/development/compilers/rust/rustc.nix
index 06d9de15ab8d..43d603923c97 100644
--- a/pkgs/development/compilers/rust/rustc.nix
+++ b/pkgs/development/compilers/rust/rustc.nix
@@ -163,6 +163,7 @@ in stdenv.mkDerivation rec {
   ];
 
   buildInputs = [ openssl ]
+    # TODO: remove libiconv once 1.66 is used to bootstrap
     ++ optionals stdenv.isDarwin [ libiconv Security ]
     ++ optional (!withBundledLLVM) llvmShared;