diff --git a/builder/default.nix b/builder/default.nix
index 0c8bd0b..d0b4e72 100644
--- a/builder/default.nix
+++ b/builder/default.nix
@@ -222,154 +222,151 @@ let
         inherit go modulesStruct localReplaceCommands defaultPackage;
       };
 
-      package =
-        lib.warnIf (buildFlags != "" || buildFlagsArray != "")
-          "Use the `ldflags` and/or `tags` attributes instead of `buildFlags`/`buildFlagsArray`"
-          stdenv.mkDerivation
-          (lib.optionalAttrs (defaultPackage != "")
-            {
-              pname = attrs.pname or baseNameOf defaultPackage;
-              version = stripVersion (modulesStruct.mod.${defaultPackage}).version;
-              src = vendorEnv.passthru.sources.${defaultPackage};
-            } // lib.optionalAttrs (lib.hasAttr "subPackages" modulesStruct) {
-            subPackages = modulesStruct.subPackages;
-          } // attrs // {
-            nativeBuildInputs = [ removeReferencesTo go ] ++ nativeBuildInputs;
-
-            inherit (go) GOOS GOARCH;
-
-            GO_NO_VENDOR_CHECKS = "1";
-
-            GO111MODULE = "on";
-            GOFLAGS = "-mod=vendor";
-
-            configurePhase = attrs.configurePhase or ''
-              runHook preConfigure
-
-              export GOCACHE=$TMPDIR/go-cache
-              export GOPATH="$TMPDIR/go"
-              export GOSUMDB=off
-              export GOPROXY=off
-              cd "$modRoot"
-              if [ -n "${vendorEnv}" ]; then
-                  rm -rf vendor
-                  ln -s ${vendorEnv} vendor
-              fi
-
-              runHook postConfigure
-            '';
-
-            buildPhase = attrs.buildPhase or ''
-              runHook preBuild
-
-              exclude='\(/_\|examples\|Godeps\|testdata'
-              if [[ -n "$excludedPackages" ]]; then
-                IFS=' ' read -r -a excludedArr <<<$excludedPackages
-                printf -v excludedAlternates '%s\\|' "''${excludedArr[@]}"
-                excludedAlternates=''${excludedAlternates%\\|} # drop final \| added by printf
-                exclude+='\|'"$excludedAlternates"
-              fi
-              exclude+='\)'
-
-              buildGoDir() {
-                local d; local cmd;
-                cmd="$1"
-                d="$2"
-                . $TMPDIR/buildFlagsArray
-                local OUT
-                if ! OUT="$(go $cmd $buildFlags "''${buildFlagsArray[@]}" ''${tags:+-tags=${lib.concatStringsSep "," tags}} ''${ldflags:+-ldflags="$ldflags"} -v -p $NIX_BUILD_CORES $d 2>&1)"; then
-                  if echo "$OUT" | grep -qE 'imports .*?: no Go files in'; then
-                    echo "$OUT" >&2
-                    return 1
-                  fi
-                  if ! echo "$OUT" | grep -qE '(no( buildable| non-test)?|build constraints exclude all) Go (source )?files'; then
-                    echo "$OUT" >&2
-                    return 1
-                  fi
-                fi
-                if [ -n "$OUT" ]; then
-                  echo "$OUT" >&2
-                fi
-                return 0
-              }
-
-              getGoDirs() {
-                local type;
-                type="$1"
-                if [ -n "$subPackages" ]; then
-                  echo "$subPackages" | sed "s,\(^\| \),\1./,g"
-                else
-                  find . -type f -name \*$type.go -exec dirname {} \; | grep -v "/vendor/" | sort --unique | grep -v "$exclude"
-                fi
-              }
-
-              if (( "''${NIX_DEBUG:-0}" >= 1 )); then
-                buildFlagsArray+=(-x)
-              fi
-
-              if [ ''${#buildFlagsArray[@]} -ne 0 ]; then
-                declare -p buildFlagsArray > $TMPDIR/buildFlagsArray
-              else
-                touch $TMPDIR/buildFlagsArray
-              fi
-              if [ -z "$enableParallelBuilding" ]; then
-                  export NIX_BUILD_CORES=1
-              fi
-              for pkg in $(getGoDirs ""); do
-                echo "Building subPackage $pkg"
-                buildGoDir install "$pkg"
-              done
-            '' + lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''
-              # normalize cross-compiled builds w.r.t. native builds
-              (
-                dir=$GOPATH/bin/${go.GOOS}_${go.GOARCH}
-                if [[ -n "$(shopt -s nullglob; echo $dir/*)" ]]; then
-                  mv $dir/* $dir/..
-                fi
-                if [[ -d $dir ]]; then
-                  rmdir $dir
-                fi
-              )
-            '' + ''
-              runHook postBuild
-            '';
-
-            doCheck = attrs.doCheck or true;
-            checkPhase = attrs.checkPhase or ''
-              runHook preCheck
-
-              for pkg in $(getGoDirs test); do
-                buildGoDir test $checkFlags "$pkg"
-              done
-
-              runHook postCheck
-            '';
-
-            installPhase = attrs.installPhase or ''
-              runHook preInstall
-
-              mkdir -p $out
-              dir="$GOPATH/bin"
-              [ -e "$dir" ] && cp -r $dir $out
-
-              runHook postInstall
-            '';
-
-            preFixup = (attrs.preFixup or "") + ''
-              find $out/{bin,libexec,lib} -type f 2>/dev/null | xargs -r ${removeExpr removeReferences} || true
-            '';
-
-            strictDeps = true;
-
-            disallowedReferences = lib.optional (!allowGoReference) go;
-
-            passthru = { inherit go vendorEnv; } // passthru;
-
-            meta = { platforms = go.meta.platforms or lib.platforms.all; } // meta;
-          });
-
     in
-    package;
+    lib.warnIf (buildFlags != "" || buildFlagsArray != "")
+      "Use the `ldflags` and/or `tags` attributes instead of `buildFlags`/`buildFlagsArray`"
+      stdenv.mkDerivation
+      (lib.optionalAttrs (defaultPackage != "")
+        {
+          pname = attrs.pname or baseNameOf defaultPackage;
+          version = stripVersion (modulesStruct.mod.${defaultPackage}).version;
+          src = vendorEnv.passthru.sources.${defaultPackage};
+        } // lib.optionalAttrs (lib.hasAttr "subPackages" modulesStruct) {
+        subPackages = modulesStruct.subPackages;
+      } // attrs // {
+        nativeBuildInputs = [ removeReferencesTo go ] ++ nativeBuildInputs;
+
+        inherit (go) GOOS GOARCH;
+
+        GO_NO_VENDOR_CHECKS = "1";
+
+        GO111MODULE = "on";
+        GOFLAGS = "-mod=vendor";
+
+        configurePhase = attrs.configurePhase or ''
+          runHook preConfigure
+
+          export GOCACHE=$TMPDIR/go-cache
+          export GOPATH="$TMPDIR/go"
+          export GOSUMDB=off
+          export GOPROXY=off
+          cd "$modRoot"
+          if [ -n "${vendorEnv}" ]; then
+              rm -rf vendor
+              ln -s ${vendorEnv} vendor
+          fi
+
+          runHook postConfigure
+        '';
+
+        buildPhase = attrs.buildPhase or ''
+          runHook preBuild
+
+          exclude='\(/_\|examples\|Godeps\|testdata'
+          if [[ -n "$excludedPackages" ]]; then
+            IFS=' ' read -r -a excludedArr <<<$excludedPackages
+            printf -v excludedAlternates '%s\\|' "''${excludedArr[@]}"
+            excludedAlternates=''${excludedAlternates%\\|} # drop final \| added by printf
+            exclude+='\|'"$excludedAlternates"
+          fi
+          exclude+='\)'
+
+          buildGoDir() {
+            local d; local cmd;
+            cmd="$1"
+            d="$2"
+            . $TMPDIR/buildFlagsArray
+            local OUT
+            if ! OUT="$(go $cmd $buildFlags "''${buildFlagsArray[@]}" ''${tags:+-tags=${lib.concatStringsSep "," tags}} ''${ldflags:+-ldflags="$ldflags"} -v -p $NIX_BUILD_CORES $d 2>&1)"; then
+              if echo "$OUT" | grep -qE 'imports .*?: no Go files in'; then
+                echo "$OUT" >&2
+                return 1
+              fi
+              if ! echo "$OUT" | grep -qE '(no( buildable| non-test)?|build constraints exclude all) Go (source )?files'; then
+                echo "$OUT" >&2
+                return 1
+              fi
+            fi
+            if [ -n "$OUT" ]; then
+              echo "$OUT" >&2
+            fi
+            return 0
+          }
+
+          getGoDirs() {
+            local type;
+            type="$1"
+            if [ -n "$subPackages" ]; then
+              echo "$subPackages" | sed "s,\(^\| \),\1./,g"
+            else
+              find . -type f -name \*$type.go -exec dirname {} \; | grep -v "/vendor/" | sort --unique | grep -v "$exclude"
+            fi
+          }
+
+          if (( "''${NIX_DEBUG:-0}" >= 1 )); then
+            buildFlagsArray+=(-x)
+          fi
+
+          if [ ''${#buildFlagsArray[@]} -ne 0 ]; then
+            declare -p buildFlagsArray > $TMPDIR/buildFlagsArray
+          else
+            touch $TMPDIR/buildFlagsArray
+          fi
+          if [ -z "$enableParallelBuilding" ]; then
+              export NIX_BUILD_CORES=1
+          fi
+          for pkg in $(getGoDirs ""); do
+            echo "Building subPackage $pkg"
+            buildGoDir install "$pkg"
+          done
+        '' + lib.optionalString (stdenv.hostPlatform != stdenv.buildPlatform) ''
+          # normalize cross-compiled builds w.r.t. native builds
+          (
+            dir=$GOPATH/bin/${go.GOOS}_${go.GOARCH}
+            if [[ -n "$(shopt -s nullglob; echo $dir/*)" ]]; then
+              mv $dir/* $dir/..
+            fi
+            if [[ -d $dir ]]; then
+              rmdir $dir
+            fi
+          )
+        '' + ''
+          runHook postBuild
+        '';
+
+        doCheck = attrs.doCheck or true;
+        checkPhase = attrs.checkPhase or ''
+          runHook preCheck
+
+          for pkg in $(getGoDirs test); do
+            buildGoDir test $checkFlags "$pkg"
+          done
+
+          runHook postCheck
+        '';
+
+        installPhase = attrs.installPhase or ''
+          runHook preInstall
+
+          mkdir -p $out
+          dir="$GOPATH/bin"
+          [ -e "$dir" ] && cp -r $dir $out
+
+          runHook postInstall
+        '';
+
+        preFixup = (attrs.preFixup or "") + ''
+          find $out/{bin,libexec,lib} -type f 2>/dev/null | xargs -r ${removeExpr removeReferences} || true
+        '';
+
+        strictDeps = true;
+
+        disallowedReferences = lib.optional (!allowGoReference) go;
+
+        passthru = { inherit go vendorEnv; } // passthru;
+
+        meta = { platforms = go.meta.platforms or lib.platforms.all; } // meta;
+      });
 
 in
 {