diff --git a/pkgs/development/libraries/glib/default.nix b/pkgs/development/libraries/glib/default.nix
index 2071eb935aea..f68bd1380052 100644
--- a/pkgs/development/libraries/glib/default.nix
+++ b/pkgs/development/libraries/glib/default.nix
@@ -75,6 +75,7 @@ stdenv.mkDerivation rec {
   # internal pcre would only add <200kB, but it's relatively common
   configureFlags = [ "--with-pcre=system" ]
     ++ optional stdenv.isDarwin "--disable-compile-warnings"
+    # glibc inclues GNU libiconv, but Darwin's iconv function is good enonugh.
     ++ optional (stdenv.hostPlatform.libc != "glibc" && !stdenv.hostPlatform.isDarwin)
       "--with-libiconv=gnu"
     ++ optional stdenv.isSunOS "--disable-dtrace"