diff --git a/modules/apps.nix b/modules/apps.nix
index 0fd5d7c..e395238 100644
--- a/modules/apps.nix
+++ b/modules/apps.nix
@@ -15,7 +15,9 @@ let
   };
 
   getExe = x:
-    "${lib.getBin x}/bin/${x.meta.mainProgram or (throw ''Package ${x.name or ""} does not have meta.mainProgram set, so I don't know how to find the main executable. You can set meta.mainProgram, or pass the full path to executable, e.g. program = "''${pkg}/bin/foo"'')}";
+    "${lib.getBin x}/bin/${x.meta.mainProgram or (throw
+      ''Package ${x.name or ""} does not have meta.mainProgram set, so I don't know how to find the main executable. You can set `meta.mainProgram`, or pass the full path to executable, e.g. program = "''${pkg}/bin/foo"''
+    )}";
 
   appType = lib.types.submodule {
     options = {
diff --git a/modules/moduleWithSystem.nix b/modules/moduleWithSystem.nix
index e5c7008..bd739cc 100644
--- a/modules/moduleWithSystem.nix
+++ b/modules/moduleWithSystem.nix
@@ -9,13 +9,14 @@
         let
           system =
             config._module.args.system or
-              config._module.args.pkgs.stdenv.hostPlatform.system or
-                (throw "moduleWithSystem: Could not determine the configuration's system parameter for this module system application.");
+              config._module.args.pkgs.stdenv.hostPlatform.system or (throw
+                "moduleWithSystem: Could not determine the `system` parameter for this module set evaluation."
+              );
 
           allArgs = withSystem system (args: args);
 
           lazyArgsPerParameter = f: builtins.mapAttrs
-            (k: v: allArgs.${k} or (throw "moduleWithSystem: module argument `${k}` does not exist."))
+            (k: v: allArgs.${k} or (throw "moduleWithSystem: per-system argument `${k}` does not exist."))
             (builtins.functionArgs f);
 
           # Use reflection to make the call lazy in the argument.
diff --git a/modules/nixpkgs.nix b/modules/nixpkgs.nix
index 44df915..730af49 100644
--- a/modules/nixpkgs.nix
+++ b/modules/nixpkgs.nix
@@ -13,11 +13,13 @@
 #
 {
   config = {
-    perSystem = { inputs', lib, ... }: {
+    perSystem = { inputs', lib, options, ... }: {
       config = {
         _module.args.pkgs = lib.mkOptionDefault (
           builtins.seq
-            (inputs'.nixpkgs or (throw "flake-parts: The flake does not have a `nixpkgs` input. Please add it, or set `perSystem._module.args.pkgs` yourself."))
+            inputs'.nixpkgs or (throw
+              "flake-parts: The flake does not have a `nixpkgs` input. Please add it, or set `${options._module.args}.pkgs` yourself."
+            )
             inputs'.nixpkgs.legacyPackages
         );
       };