diff --git a/doc/release-notes/rl-2505.section.md b/doc/release-notes/rl-2505.section.md
index e949e7b451eb..e386ead66797 100644
--- a/doc/release-notes/rl-2505.section.md
+++ b/doc/release-notes/rl-2505.section.md
@@ -79,6 +79,7 @@
     - `lib.types.nullOr`
     - `lib.types.functionTo`
     - `lib.types.coercedTo`
+    - `lib.types.either`
 
 - Plasma 5 and Qt 5 based versions of associated software are deprecated in NixOS 25.05, and will be removed in NixOS 25.11. Users are encouraged to upgrade to Plasma 6.
 
diff --git a/lib/tests/modules.sh b/lib/tests/modules.sh
index 2f21e466450d..e623c0fb55b8 100755
--- a/lib/tests/modules.sh
+++ b/lib/tests/modules.sh
@@ -439,6 +439,14 @@ NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribu
 NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.coercedTo.type.functor.wrapped ./deprecated-wrapped.nix
 NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.coercedTo.type.nestedTypes.finalType.functor.wrapped ./deprecated-wrapped.nix
 NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.coercedTo.type.nestedTypes.coercedType.functor.wrapped ./deprecated-wrapped.nix
+# either
+NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.either.type.functor.wrapped ./deprecated-wrapped.nix
+NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.mergedEither.type.functor.wrapped ./deprecated-wrapped.nix
+
+NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.either.type.nestedTypes.left.functor.wrapped ./deprecated-wrapped.nix
+NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.either.type.nestedTypes.right.functor.wrapped ./deprecated-wrapped.nix
+NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.mergedEither.type.nestedTypes.left.functor.wrapped ./deprecated-wrapped.nix
+NIX_ABORT_ON_WARN=1 checkConfigError 'The deprecated `.*functor.wrapped` attribute .*is accessed, use `.*nestedTypes.elemType` instead.' options.mergedEither.type.nestedTypes.right.functor.wrapped ./deprecated-wrapped.nix
 
 # Even with multiple assignments, a type error should be thrown if any of them aren't valid
 checkConfigError 'A definition for option .* is not of type .*' \
diff --git a/lib/tests/modules/deprecated-wrapped.nix b/lib/tests/modules/deprecated-wrapped.nix
index 5559cd3e9332..c50a7d79f59f 100644
--- a/lib/tests/modules/deprecated-wrapped.nix
+++ b/lib/tests/modules/deprecated-wrapped.nix
@@ -10,6 +10,7 @@ let
     nullOr
     functionTo
     coercedTo
+    either
     ;
 in
 {
@@ -56,6 +57,12 @@ in
         options.coercedTo = mkOption {
           type = coercedTo (listOf types.str) lib.id (listOf types.str);
         };
+        options.either = mkOption {
+          type = either (listOf types.str) (listOf types.str);
+        };
+        options.mergedEither = mkOption {
+          type = either (listOf types.str) (listOf types.str);
+        };
       }
     )
     # Module B
@@ -77,6 +84,9 @@ in
         options.mergedFunctionTo = mkOption {
           type = functionTo (listOf types.str);
         };
+        options.mergedEither = mkOption {
+          type = either (listOf types.str) (listOf types.str);
+        };
       }
     )
   ];
diff --git a/lib/types.nix b/lib/types.nix
index a03c673c1068..ee1410127b1a 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -1134,13 +1134,13 @@ rec {
                then t2.merge loc defs
           else mergeOneOption loc defs;
       typeMerge = f':
-        let mt1 = t1.typeMerge (elemAt f'.wrapped 0).functor;
-            mt2 = t2.typeMerge (elemAt f'.wrapped 1).functor;
+        let mt1 = t1.typeMerge (elemAt f'.payload.elemType 0).functor;
+            mt2 = t2.typeMerge (elemAt f'.payload.elemType 1).functor;
         in
            if (name == f'.name) && (mt1 != null) && (mt2 != null)
            then functor.type mt1 mt2
            else null;
-      functor = (defaultFunctor name) // { wrapped = [ t1 t2 ]; };
+      functor = elemTypeFunctor name { elemType = [ t1 t2 ]; };
       nestedTypes.left = t1;
       nestedTypes.right = t2;
     };