diff --git a/nixos/modules/services/web-servers/apache-httpd/default.nix b/nixos/modules/services/web-servers/apache-httpd/default.nix
index dc0ca501a48..ed77e084476 100644
--- a/nixos/modules/services/web-servers/apache-httpd/default.nix
+++ b/nixos/modules/services/web-servers/apache-httpd/default.nix
@@ -63,6 +63,8 @@ let
       let
         svcFunction =
           if svc ? function then svc.function
+          # instead of using serviceType="mediawiki"; you can copy mediawiki.nix to any location outside nixpkgs, modify it at will, and use serviceExpression=./mediawiki.nix;
+          else if svc ? serviceExpression then import (toString svc.serviceExpression)
           else import (toString "${toString ./.}/${if svc ? serviceType then svc.serviceType else svc.serviceName}.nix");
         config = (evalModules
           { modules = [ { options = res.options; config = svc.config or svc; } ];