diff --git a/pkgs/development/libraries/libassuan/default.nix b/pkgs/development/libraries/libassuan/default.nix
index 3a00ca498cbe..e2fbb3f9287c 100644
--- a/pkgs/development/libraries/libassuan/default.nix
+++ b/pkgs/development/libraries/libassuan/default.nix
@@ -16,6 +16,7 @@ stdenv.mkDerivation rec {
   buildInputs = [ npth gettext ];
 
   configureFlags = [
+    # Required for cross-compilation.
     "--with-libgpg-error-prefix=${libgpg-error.dev}"
   ];