diff --git a/pkgs/lib/modules.nix b/pkgs/lib/modules.nix
index 81a4c43b2a9..10667dc3ade 100644
--- a/pkgs/lib/modules.nix
+++ b/pkgs/lib/modules.nix
@@ -54,9 +54,10 @@ rec {
         removeAttrs (delayProperties m) ["require"];
     in
       if isModule m then
-        m
+        { key = "<unknow location>"; } // m
       else
         {
+          key = "<unknow location>";
           imports = getImportedPaths m;
           config = getConfig m;
         } // (
@@ -72,8 +73,7 @@ rec {
       moduleImport = m:
         (unifyModuleSyntax (applyIfFunction (importIfPath m) args)) // {
           # used by generic closure to avoid duplicated imports.
-          key = if isPath m then m else
-            /bad/developer/implies/bad/error/messages;
+          key = if isPath m then m else "<unknow location>";
         };
 
       getImports = m: attrByPath ["imports"] [] m;
@@ -188,9 +188,25 @@ rec {
         moduleZip {
           options = lib.zip (name: values:
             if any isOption values then
-              addOptionMakeUp
-                { name = addName name; recurseInto = recurseForOption; }
-                (mergeOptionDecls values)
+              let
+                # locations to sub-options declarations
+                decls =
+                  map (m:
+                    mapSubOptions (subModule:
+                      let module = lib.applyIfFunction subModule {}; in
+                      if lib.isModule module then
+                        { inherit (m) key; } // subModule
+                      else
+                        args: {
+                          inherit (m) key;
+                          options = lib.applyIfFunction subModule args;
+                        }
+                    ) m.options
+                  ) (declarationsOf name);
+              in
+                addOptionMakeUp
+                  { name = addName name; recurseInto = recurseForOption; }
+                  (mergeOptionDecls decls)
             else if all isAttrs values then
               (recurseInto name modules).options
             else
diff --git a/pkgs/lib/options.nix b/pkgs/lib/options.nix
index 37d092ef3c5..6aad285b7ac 100644
--- a/pkgs/lib/options.nix
+++ b/pkgs/lib/options.nix
@@ -27,6 +27,14 @@ rec {
     # options (set of sub-options declarations & definitions)
   };
 
+  mapSubOptions = f: opt:
+    if opt ? options then
+      opt // {
+        options = map f (toList opt.options);
+      }
+    else
+      opt;
+
   # Make the option declaration more user-friendly by adding default
   # settings and some verifications based on the declaration content (like
   # type correctness).
@@ -68,20 +76,6 @@ rec {
           }
         else opt;
 
-      convertOptionsToModules = opt:
-        if opt ? options then
-          opt // {
-            options = map (decl:
-              let module = lib.applyIfFunction decl {}; in
-              if lib.isModule module then
-                decl
-              else
-                arg: { options = lib.applyIfFunction decl arg; }
-            ) opt.options;
-          }
-        else
-          opt;
-
       handleOptionSets = opt:
         if decl ? type && decl.type.hasOptions then
           let
@@ -119,7 +113,6 @@ rec {
         # override settings
         ensureMergeInputType
         ensureDefaultType
-        convertOptionsToModules
         handleOptionSets
       ];