diff --git a/builder/default.nix b/builder/default.nix
index 0ee410f..07b4bd9 100644
--- a/builder/default.nix
+++ b/builder/default.nix
@@ -5,7 +5,7 @@
 , packageDefinitions
 , name
 , nixpkgs
-, system ? (if builtins.isAttrs nixpkgs && nixpkgs ? system then nixpkgs.system else import ./builder_error.nix)
+, system ? (nixpkgs.system or import ./builder_error.nix)
 , extra_pkg_config ? {}
 , dependencyOverlays ? null
 , nixCats_passthru ? {}
@@ -16,16 +16,13 @@ let
       else (nixpkgs.config or {}) // extra_pkg_config;
     overlays = if isList dependencyOverlays
       then dependencyOverlays
-      else if isAttrs dependencyOverlays && hasAttr system dependencyOverlays
-      then dependencyOverlays.${system}
-      else if isNull dependencyOverlays then []
-      else import ./builder_error.nix;
+      else dependencyOverlays.${system} or
+      (if isNull dependencyOverlays then []
+      else import ./builder_error.nix);
   in if isAttrs nixCats_passthru && isFunction categoryDefinitions
-    && isAttrs packageDefinitions && isString name then
-  import (
-    if isAttrs nixpkgs && nixpkgs ? path && ! nixpkgs ? outPath
-    then nixpkgs.path else nixpkgs
-  ) { inherit system config overlays; }
+    && isAttrs packageDefinitions && isString name
+  then import (nixpkgs.path or nixpkgs.outPath or nixpkgs)
+    { inherit system config overlays; }
   else import ./builder_error.nix;
 
   ncTools = import ./ncTools.nix { inherit (pkgs) lib; };
diff --git a/utils/default.nix b/utils/default.nix
index ed96db1..87203b7 100644
--- a/utils/default.nix
+++ b/utils/default.nix
@@ -8,7 +8,7 @@ with builtins; rec {
       luaPath:
       {
         nixpkgs
-        , system ? (if isAttrs nixpkgs && nixpkgs ? system then nixpkgs.system else import ../builder/builder_error.nix)
+        , system ? (nixpkgs.system or import ../builder/builder_error.nix)
         , extra_pkg_config ? {}
         , dependencyOverlays ? null
         , nixCats_passthru ? {}
@@ -24,20 +24,15 @@ with builtins; rec {
           else if isPath nixpkgs || isString nixpkgs then "path"
           else if isAttrs nixpkgs && (lib.isDerivation nixpkgs || nixpkgs ? outPath) then "drv"
           else import ../builder/builder_error.nix;
-        nixpkgspath = if pkgstype == "drv" then nixpkgs.outPath else if pkgstype == "pkgs" then nixpkgs.path else nixpkgs;
-        nixlib = if pkgstype == "pkgs" || pkgstype == "nixpkgs"
-          then nixpkgs.lib
-          else import "${nixpkgspath}/lib";
-        newnixpkgs = if pkgstype == "nixpkgs"
-          then nixpkgs
-          else if pkgstype == "pkgs"
-          then nixpkgs // { outPath = nixpkgspath; }
+        nixpkgspath = if pkgstype == "pkgs" then nixpkgs.path else nixpkgs.outPath or nixpkgs;
+        newnixpkgs = if pkgstype == "nixpkgs" then nixpkgs
+          else if pkgstype == "pkgs" then nixpkgs // { outPath = nixpkgspath; }
           else {
-            lib = nixlib;
+            lib = nixpkgs.lib or import "${nixpkgspath}/lib";
             outPath = nixpkgspath;
           };
       in
-      nixlib.makeOverridable (import ../builder) {
+      newnixpkgs.lib.makeOverridable (import ../builder) {
         nixpkgs = newnixpkgs;
         inherit luaPath categoryDefinitions packageDefinitions name
         system extra_pkg_config dependencyOverlays nixCats_passthru;