diff --git a/src/buildMutations/index.ts b/src/buildMutations/index.ts
index 472a1a0..c1b6420 100644
--- a/src/buildMutations/index.ts
+++ b/src/buildMutations/index.ts
@@ -12,7 +12,7 @@ type SubMutations = {
 }
 
 function buildMutations(
-    mutations :Dictionary<Mutation> = {},
+    mutations :Dictionary<Mutation|([Mutation,boolean|undefined])> = {},
     subduxes = {}
 ) {
   // we have to differentiate the subduxes with '*' than those
@@ -49,15 +49,26 @@ function buildMutations(
 
   nonGlobby.forEach(([slice, {mutations = {}, reducer = {}}]:any[]) => {
     Object.entries(mutations).forEach(([type, mutation]) => {
-      const localized = (payload = null, action :Action) =>
-        u.updateIn(slice)((mutation as Mutation)(payload, action));
+      const localized = (payload = null, action :Action) => {
+          console.log(slice);
+
+        return u.updateIn(slice)((mutation as Mutation)(payload, action));
+      }
 
       mergedMutations[type].push(localized);
     });
   });
 
   Object.entries(mutations).forEach(([type, mutation]) => {
-    mergedMutations[type].push(mutation);
+    if ( Array.isArray(mutation) ) {
+        if( mutation[1] ) {
+            mergedMutations[type] = [
+                mutation[0]
+            ]
+        }
+        else mergedMutations[type].push( mutation[0] );
+    }
+    else mergedMutations[type].push(mutation);
   });
 
   return fp.mapValues(composeMutations)(mergedMutations);
diff --git a/src/sink.test.ts b/src/sink.test.ts
new file mode 100644
index 0000000..96ebe38
--- /dev/null
+++ b/src/sink.test.ts
@@ -0,0 +1,39 @@
+import Updux from './updux';
+
+const foo = new Updux<number>({
+  initial: 0,
+  mutations: {
+    doIt: () => (state: number) => {
+      console.log(state);
+      return state + 1;
+    },
+  },
+});
+
+const bar = new Updux<{foo: number}>({
+  subduxes: {foo},
+  mutations: {
+    doIt: () => (state: any) => state,
+  },
+});
+
+bar.addMutation(
+  foo.actions.doIt,
+  () => (state: any) => ({...state, bar: 'yay'}),
+  true,
+);
+
+test('initial', () => {
+  expect(bar.initial).toEqual({foo: 0});
+});
+
+test('foo alone', () => {
+  expect(foo.reducer(undefined, foo.actions.doIt())).toEqual(1);
+});
+
+test('sink mutations', () => {
+  expect(bar.reducer(undefined, bar.actions.doIt())).toEqual({
+    foo: 0,
+    bar: 'yay',
+  });
+});
diff --git a/src/updux.ts b/src/updux.ts
index a159b50..76a268a 100644
--- a/src/updux.ts
+++ b/src/updux.ts
@@ -42,12 +42,12 @@ export type Dux<S> = Pick<
 >;
 
 /**
-  * `Updux` is a way to minimize and simplify the boilerplate associated with the
-  * creation of a `Redux` store. It takes a shorthand configuration
-  * object, and generates the appropriate reducer, actions, middleware, etc.
-  * In true `Redux`-like fashion, upduxes can be made of sub-upduxes (`subduxes` for short) for different slices of the root state.
-  * @typeparam S Store's state type. Defaults to `any`.
-  */
+ * `Updux` is a way to minimize and simplify the boilerplate associated with the
+ * creation of a `Redux` store. It takes a shorthand configuration
+ * object, and generates the appropriate reducer, actions, middleware, etc.
+ * In true `Redux`-like fashion, upduxes can be made of sub-upduxes (`subduxes` for short) for different slices of the root state.
+ * @typeparam S Store's state type. Defaults to `any`.
+ */
 export class Updux<S = any> {
   subduxes: Dictionary<Updux>;
 
@@ -60,41 +60,41 @@ export class Updux<S = any> {
    */
   initial: S;
 
-/**
-  * Function that can be provided to alter all local mutations of the updux
-  * (the mutations of subduxes are left untouched).
-  *
-  * Can be used, for example, for Immer integration:
-  *
-  * ```
-  * import Updux from 'updux';
-  * import { produce } from 'Immer';
-  *
-  * const updux = new Updux({
-  *     initial: { counter: 0 },
-  *     groomMutations: mutation => (...args) => produce( mutation(...args) ),
-  *     mutations: {
-  *         add: (inc=1) => draft => draft.counter += inc
-  *     }
-  * });
-  *
-  * ```
-  *
-  * Or perhaps for debugging:
-  *
-  * ```
-  * import Updux from 'updux';
-  *
-  * const updux = new Updux({
-  *     initial: { counter: 0 },
-  *     groomMutations: mutation => (...args) => state => {
-  *         console.log( "got action ", args[1] );
-  *         return mutation(...args)(state);
-  *     }
-  * });
-  *
-  * ```
-  */
+  /**
+   * Function that can be provided to alter all local mutations of the updux
+   * (the mutations of subduxes are left untouched).
+   *
+   * Can be used, for example, for Immer integration:
+   *
+   * ```
+   * import Updux from 'updux';
+   * import { produce } from 'Immer';
+   *
+   * const updux = new Updux({
+   *     initial: { counter: 0 },
+   *     groomMutations: mutation => (...args) => produce( mutation(...args) ),
+   *     mutations: {
+   *         add: (inc=1) => draft => draft.counter += inc
+   *     }
+   * });
+   *
+   * ```
+   *
+   * Or perhaps for debugging:
+   *
+   * ```
+   * import Updux from 'updux';
+   *
+   * const updux = new Updux({
+   *     initial: { counter: 0 },
+   *     groomMutations: mutation => (...args) => state => {
+   *         console.log( "got action ", args[1] );
+   *         return mutation(...args)(state);
+   *     }
+   * });
+   *
+   * ```
+   */
   groomMutations: (mutation: Mutation<S>) => Mutation<S>;
 
   @observable private localEffects: Dictionary<
@@ -103,7 +103,9 @@ export class Updux<S = any> {
 
   @observable private localActions: Dictionary<ActionCreator>;
 
-  @observable private localMutations: Dictionary<Mutation<S>>;
+  @observable private localMutations: Dictionary<
+    Mutation<S> | [Mutation<S>, boolean | undefined]
+  >;
 
   constructor(config: UpduxConfig = {}) {
     this.groomMutations = config.groomMutations || ((x: Mutation<S>) => x);
@@ -245,6 +247,8 @@ export class Updux<S = any> {
    * Adds a mutation and its associated action to the updux.
    * If a local mutation was already associated to the action,
    * it will be replaced by the new one.
+   * @param isSink
+   * If `true`, disables the subduxes mutations for this action.
    * @example
    * ```
    * updux.addMutation( add, inc => state => state + inc );
@@ -253,11 +257,13 @@ export class Updux<S = any> {
   addMutation<A extends ActionCreator>(
     creator: A,
     mutation: Mutation<S, A extends (...args: any[]) => infer R ? R : never>,
+    isSink?: boolean,
   ) {
     this.localActions[creator.type] = creator;
-    this.localMutations[creator.type] = this.groomMutations(
-      mutation as any,
-    ) as Mutation<S>;
+    this.localMutations[creator.type] = [
+      this.groomMutations(mutation as any) as Mutation<S>,
+      isSink,
+    ];
   }
 }