diff --git a/lib/modules.nix b/lib/modules.nix
index 2294585723ba..f5b8af0e9858 100644
--- a/lib/modules.nix
+++ b/lib/modules.nix
@@ -763,17 +763,24 @@ let
               };
             };
 
-          mergedType' =
-            if mergedType ? functor.wrappedDeprecationMessage then
-              addDeprecatedWrapped mergedType
-            else
-              mergedType;
-
           typeSet =
-            if (bothHave "type") && typesMergeable then
-              { type = mergedType'; }
-            else if opt.options ? type && opt.options.type ? functor.wrappedDeprecationMessage then
-              { type = addDeprecatedWrapped opt.options.type; }
+            if opt.options ? type then
+              if res ? type then
+                if typesMergeable then
+                  {
+                    type =
+                      if mergedType ? functor.wrappedDeprecationMessage then
+                        addDeprecatedWrapped mergedType
+                      else
+                        mergedType;
+                  }
+                else
+                  # Keep in sync with the same error below!
+                  throw "The option `${showOption loc}' in `${opt._file}' is already declared in ${showFiles res.declarations}."
+              else if opt.options.type ? functor.wrappedDeprecationMessage then
+                { type = addDeprecatedWrapped opt.options.type; }
+              else
+                {}
             else
               {};
 
@@ -782,9 +789,9 @@ let
       if bothHave "default" ||
          bothHave "example" ||
          bothHave "description" ||
-         bothHave "apply" ||
-         (bothHave "type" && (! typesMergeable))
+         bothHave "apply"
       then
+        # Keep in sync with the same error above!
         throw "The option `${showOption loc}' in `${opt._file}' is already declared in ${showFiles res.declarations}."
       else
         let