diff --git a/default.nix b/default.nix
index 39c83eaff..1d3cc4288 100644
--- a/default.nix
+++ b/default.nix
@@ -14,6 +14,9 @@ let
 in
 mixRelease rec {
   pname = "mobilizon";
+
+  # This has to be kept in sync with the version in mix.exs and package.json!
+  # Otherwise the nginx routing isn't going to work properly.
   version = "4.1.0-alpha.1";
 
   inherit src;