diff --git a/pkgs/top-level/lua-packages.nix b/pkgs/top-level/lua-packages.nix
index 7a0b0a56c9b4..f233ae43ad10 100644
--- a/pkgs/top-level/lua-packages.nix
+++ b/pkgs/top-level/lua-packages.nix
@@ -619,7 +619,7 @@ let
     # NOTE: For updating, new Lua mpack bindings live at:
     # https://github.com/libmpack/libmpack-lua.
     src = libmpack.src;
-    sourceRoot = "libmpack-${libmpack.rev}-src/binding/lua";
+    sourceRoot = "${src.name}/binding/lua";
 
     nativeBuildInputs = [ pkgconfig ];
     buildInputs = [ libmpack ]; # ++ [ libtool lua ];