diff --git a/builder/default.nix b/builder/default.nix
index 5131fd3..e55d6c6 100644
--- a/builder/default.nix
+++ b/builder/default.nix
@@ -8,6 +8,7 @@
 , jq
 , cacert
 , pkgs
+, pkgsBuildBuild
 }:
 let
 
@@ -18,9 +19,10 @@ let
   # Internal only build-time attributes
   internal =
     let
-      mkInternalPkg = name: src: pkgs.runCommand "gomod2nix-${name}"
+      mkInternalPkg = name: src: pkgsBuildBuild.runCommand "gomod2nix-${name}"
         {
-          nativeBuildInputs = [ pkgs.go ];
+          inherit (pkgsBuildBuild.go) GOOS GOARCH;
+          nativeBuildInputs = [ pkgsBuildBuild.go ];
         } ''
         export HOME=$(mktemp -d)
         cp ${src} src.go
diff --git a/default.nix b/default.nix
index 6d4a0bf..7c5e96d 100644
--- a/default.nix
+++ b/default.nix
@@ -20,7 +20,7 @@ buildGoApplication {
 
   nativeBuildInputs = [ makeWrapper installShellFiles ];
 
-  postInstall = lib.optionalString (stdenv.hostPlatform == stdenv.targetPlatform) ''
+  postInstall = lib.optionalString (stdenv.buildPlatform == stdenv.targetPlatform) ''
     $out/bin/gomod2nix completion bash > gomod2nix.bash
     $out/bin/gomod2nix completion fish > gomod2nix.fish
     $out/bin/gomod2nix completion zsh > _gomod2nix