diff --git a/impure.nix b/impure.nix
index 2d39bf1ae..929d4bf84 100644
--- a/impure.nix
+++ b/impure.nix
@@ -24,19 +24,20 @@ let
     pkgs.sops-nix.nixosModules.sops
   ];
   mkFlavoredHost = args: let
-    host = evalHost args;
+    plainHost = evalHost args;
     # expose the toplevel nixos system as the toplevel attribute itself,
     # with nested aliases for other common build targets
-  in host.config.system.build.toplevel.overrideAttrs (base: {
-    passthru = (base.passthru or {}) // {
-      config = host.config;
-      fs = host.config.sane.fs;
-      img = host.config.system.build.img;
-      pkgs = host.config.system.build.pkgs;
-      programs = builtins.mapAttrs (_: p: p.package) host.config.sane.programs;
-      toplevel = host.config.system.build.toplevel;  #< self
-    };
-  });
+    addPassthru = host: host.config.system.build.toplevel.overrideAttrs (base: {
+      passthru = (base.passthru or {}) // {
+        inherit (host) config;
+        inherit (host.config.sane) fs;
+        inherit (host.config.system.build) imgs pkgs;
+        programs = builtins.mapAttrs (_: p: p.package) host.config.sane.programs;
+        toplevel = host.config.system.build.toplevel;  #< self
+        extendModules = arg: addPassthru (host.extendModules arg);
+      };
+    });
+  in addPassthru plainHost;
   mkHost = args: {
     # TODO: swap order: $host-{next,staging}-{min,light}:
     # then lexicographically-adjacent targets would also have the minimal difference in closure,