diff --git a/modules/impurity.nix b/modules/impurity.nix
index b6cc507..14356d3 100644
--- a/modules/impurity.nix
+++ b/modules/impurity.nix
@@ -1,6 +1,6 @@
 self: { lib, config, pkgs, ... }: with lib; let
   relativePath = path: assert types.path.check path;
-    with builtins; strings.removePrefix ("${toString self}") (toString path);
+    with builtins; strings.removePrefix (toString self) (toString path);
 
   impurityGroupEnabled = group: let
     impurityGroups = strings.splitString " " (builtins.getEnv "IMPURITY_GROUPS");
@@ -10,9 +10,13 @@ self: { lib, config, pkgs, ... }: with lib; let
     impurePathEnv = builtins.getEnv "IMPURITY_PATH";
   in if impurePathEnv == ""
      then throw "impurity.enable is true but IMPURITY_PATH is not set"
-     else /. + impurePathEnv;
+     else impurePathEnv;
+
+  createImpurePath = path: let
+    relative = (relativePath path);
+    full = impurePath + relative;
+  in pkgs.runCommand "impurity-${relative}" {} "ln -s ${full} $out";
 
-  createImpurePath = path: impurePath + (relativePath path);
 in {
   options.impurity.enable = mkOption {
     type = types.bool;