diff --git a/types/index.d.ts b/types/index.d.ts
index db56861f1..4c4e43e64 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -28,7 +28,7 @@ export declare class Store<S> {
 
   hotUpdate(options: {
     actions?: ActionTree<S, S>;
-    mutations?: MutationTree<S, S>;
+    mutations?: MutationTree<S>;
     getters?: GetterTree<S, S>;
     modules?: ModuleTree<S>;
   }): void;
@@ -48,7 +48,6 @@ export interface Commit {
 
 export interface ActionContext<S, R> {
   dispatch: Dispatch;
-
   commit: Commit;
   state: S;
   getters: any;
@@ -81,7 +80,7 @@ export interface StoreOptions<S> {
   state?: S;
   getters?: GetterTree<S, S>;
   actions?: ActionTree<S, S>;
-  mutations?: MutationTree<S, S>;
+  mutations?: MutationTree<S>;
   modules?: ModuleTree<S>;
   plugins?: Plugin<S>[];
   strict?: boolean;
@@ -95,7 +94,7 @@ export interface ActionObject<S, R> {
 
 export type Getter<S, R> = (state: S, getters: any, rootState: R, rootGetters: any) => any;
 export type Action<S, R> = ActionHandler<S, R> | ActionObject<S, R>;
-export type Mutation<S, R> = (this: Store<R>, state: S, payload: any) => any;
+export type Mutation<S> = (state: S, payload: any) => any;
 export type Plugin<S> = (store: Store<S>) => any;
 
 export interface Module<S, R> {
@@ -103,7 +102,7 @@ export interface Module<S, R> {
   state?: S | (() => S);
   getters?: GetterTree<S, R>;
   actions?: ActionTree<S, R>;
-  mutations?: MutationTree<S, R>;
+  mutations?: MutationTree<S>;
   modules?: ModuleTree<R>;
 }
 
@@ -119,8 +118,8 @@ export interface ActionTree<S, R> {
   [key: string]: Action<S, R>;
 }
 
-export interface MutationTree<S, R> {
-  [key: string]: Mutation<S, R>;
+export interface MutationTree<S> {
+  [key: string]: Mutation<S>;
 }
 
 export interface ModuleTree<R> {
diff --git a/types/test/index.ts b/types/test/index.ts
index 68469bf6d..ca03458d9 100644
--- a/types/test/index.ts
+++ b/types/test/index.ts
@@ -67,9 +67,7 @@ namespace RootModule {
       }
     },
     mutations: {
-      bar (state, payload) {
-        this.state.value;
-      }
+      bar (state, payload) {}
     },
     strict: true
   });
@@ -94,9 +92,7 @@ namespace RootDefaultModule {
       }
     },
     mutations: {
-      bar (state, payload) {
-        this.state.value;
-      }
+      bar (state, payload) {}
     },
     strict: true
   });
@@ -163,11 +159,6 @@ namespace NestedModules {
               foo(context: ActionStore, payload) {
                 this.state.a;
               }
-            },
-            mutations: {
-              bar(state, payload) {
-                this.state.b.e;
-              }
             }
           }
         }