diff --git a/mcu-contrib/default.nix b/mcu-contrib/default.nix
index c4c20f1..901dbc7 100644
--- a/mcu-contrib/default.nix
+++ b/mcu-contrib/default.nix
@@ -36,7 +36,6 @@ let
       inherit patchPhase;
       nativeBuildInputs = [ pkgs.llvm ] ++ extraNativeBuildInputs;
       buildPhase = ''
-        rustc --version
         export CARGO_HOME=$(mktemp -d cargo-home.XXX)
         cargo build --release --bin ${binaryName} ${extraCargoBuildArgs}
       '';
@@ -68,9 +67,6 @@ in
           --replace "[10, 34, 16, 10];" \
                     "[192, 168, 1, 10];"  # or other default MQTT broker address
       '';
-      outputHashes = {
-        "heapless-0.7.7" = "sha256-4TfpXSR84aL1u/UZ7dHDLH9lGeuuGxCOcgu1HruUBTY=";
-      };
       doCheck = false;
     } // value))) {
       dual-iir = {};