diff --git a/src/Updux.ts b/src/Updux.ts
index b9358a9..d35b81c 100644
--- a/src/Updux.ts
+++ b/src/Updux.ts
@@ -116,6 +116,7 @@ export default class Updux<
             this.initial,
             this.#localMutations,
             this.#defaultMutation,
+            this.#subduxes,
         ) as any as (
             state: undefined | typeof this.initial,
             action: Action,
diff --git a/src/mutations.test.ts b/src/mutations.test.ts
index 9f19df8..5858b63 100644
--- a/src/mutations.test.ts
+++ b/src/mutations.test.ts
@@ -56,18 +56,25 @@ test('default mutation', () => {
 
 test('mutation of a subdux', () => {
     const baz = createAction('baz');
+    const noop = createAction('noop');
+    const stopit = createAction('stopit');
 
     const bar = new Updux({
         initial: 0,
         actions: {
             baz,
+            stopit,
         },
     });
     bar.addMutation(baz, () => () => 1);
+    bar.addMutation(stopit, () => () => 2);
 
     const foo = new Updux({
         subduxes: { bar },
     });
+    foo.addMutation(stopit, () => (state) => state, true);
 
+    expect(foo.reducer(undefined, noop())).toHaveProperty('bar', 0);
     expect(foo.reducer(undefined, baz())).toHaveProperty('bar', 1);
+    expect(foo.reducer(undefined, stopit())).toHaveProperty('bar', 0);
 });
diff --git a/src/reducer.ts b/src/reducer.ts
index 12b431c..9ca2571 100644
--- a/src/reducer.ts
+++ b/src/reducer.ts
@@ -16,8 +16,7 @@ export function buildReducer(
     defaultMutation?: Omit<MutationCase, 'matcher'>,
     subduxes: Record<string, Dux> = {},
 ) {
-    // const subReducers =
-    //         ? R.mapValues(subduxes, R.prop('reducer'));
+    const subReducers = R.mapValues(subduxes, R.prop('reducer'));
 
     // TODO matcherMutation
     // TODO defaultMutation
@@ -48,6 +47,16 @@ export function buildReducer(
             )(state);
         }
 
+        if (!terminal && Object.keys(subduxes).length > 0) {
+            // subduxes
+            state = R.merge(
+                state,
+                R.mapValues(subReducers, (reducer, slice) =>
+                    (reducer as any)(state[slice], action),
+                ),
+            );
+        }
+
         return state;
     };