diff --git a/lib/default.nix b/lib/default.nix
index 1af41db..906bf70 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -56,7 +56,7 @@ in
       oizys-zig = pkgs.callPackage ../pkgs/oizys/oizys-zig { inherit zig2nix; };
       oizys-nim = pkgs.callPackage ../pkgs/oizys/oizys-nim { };
       oizys-rs = pkgs.callPackage ../pkgs/oizys/oizys-rs { };
-      oizys-go = pkgs.callPackage ../pkgs/oizys/oizys-go { inherit self;};
+      oizys-go = pkgs.callPackage ../pkgs/oizys/oizys-go { inherit self lib; };
       default = oizys-go;
     });
     devShells = forAllSystems (pkgs: {
diff --git a/lib/extended.nix b/lib/extended.nix
index 4a064e3..f5d14a6 100644
--- a/lib/extended.nix
+++ b/lib/extended.nix
@@ -1,12 +1,14 @@
 final: prev:
 let
   inherit (final)
+    concatStringsSep
     hasSuffix
     mkEnableOption
     mkIf
     mkOption
     types
     ;
+  inherit (builtins) listToAttrs substring;
 in
 rec {
   enabled = {
@@ -19,7 +21,7 @@ rec {
   # ["a" "b"] -> {a.enable = true; b.enable = true;}
   enableAttrs =
     attrs:
-    builtins.listToAttrs (
+    listToAttrs (
       map (attr: {
         name = attr;
         value = enabled;
@@ -28,7 +30,7 @@ rec {
   # ["a" "b"] -> {a.enable = false; b.enable = false;}
   disableAttrs =
     attrs:
-    builtins.listToAttrs (
+    listToAttrs (
       map (attr: {
         name = attr;
         value = disabled;
@@ -50,4 +52,13 @@ rec {
     };
     config = mkIf config.oizys.${attr}.enable content;
   };
+
+  # generate date string with '-' from long date
+  mkDate =
+    longDate:
+    (concatStringsSep "-" [
+      (substring 0 4 longDate)
+      (substring 4 2 longDate)
+      (substring 6 2 longDate)
+    ]);
 }
diff --git a/modules/nix.nix b/modules/nix.nix
index 36ccc72..e66deb9 100644
--- a/modules/nix.nix
+++ b/modules/nix.nix
@@ -26,7 +26,6 @@
     pkgs.nixfmt-rfc-style
     pkgs.nix-output-monitor
 
-
     self.packages.${pkgs.system}.default
   ];
 
diff --git a/pkgs/oizys/oizys-go/default.nix b/pkgs/oizys/oizys-go/default.nix
index f1123c7..4ae8cdd 100644
--- a/pkgs/oizys/oizys-go/default.nix
+++ b/pkgs/oizys/oizys-go/default.nix
@@ -8,20 +8,14 @@
   nix-output-monitor,
   ...
 }:
-let 
-mkDate =
-    longDate:
-    (lib.concatStringsSep "-" [
-      (builtins.substring 0 4 longDate)
-      (builtins.substring 4 2 longDate)
-      (builtins.substring 6 2 longDate)
-    ]);
+let
+  inherit (lib) mkDate cleanSource makeBinPath;
 in
 buildGoModule {
   pname = "oizys";
-  version = "date=${mkDate self.lastModifiedDate}";
+  version = "d${mkDate self.lastModifiedDate}";
 
-  src = lib.cleanSource ./.;
+  src = cleanSource ./.;
   vendorHash = "sha256-Geqcp0/7I1IF2IfaYyIChz7SOCF+elIEdcz2VsAU0hQ=";
 
   nativeBuildInputs = [
@@ -36,6 +30,11 @@ buildGoModule {
 
   postFixup = ''
     wrapProgram $out/bin/oizys \
-      --prefix PATH ':' ${lib.makeBinPath [ gh nix-output-monitor ]}
+      --prefix PATH ':' ${
+        makeBinPath [
+          gh
+          nix-output-monitor
+        ]
+      }
   '';
 }