diff --git a/build.nix b/build.nix
index c25fbba..f1552c4 100644
--- a/build.nix
+++ b/build.nix
@@ -244,6 +244,7 @@ let
       mkdir -p $CARGO_HOME
 
       cp "$cargoconfig" $CARGO_HOME/config.toml
+      # symlink for backwards compatibility with older cargo
       ln -s ./config.toml $CARGO_HOME/config
 
       runHook postConfigure