diff --git a/types/react/index.d.ts b/types/react/index.d.ts
index d9c4418b82..c5c1c76d17 100644
--- a/types/react/index.d.ts
+++ b/types/react/index.d.ts
@@ -282,8 +282,9 @@ declare namespace React {
 
         // We MUST keep setState() as a unified signature because it allows proper checking of the method return type.
         // See: https://github.com/DefinitelyTyped/DefinitelyTyped/issues/18365#issuecomment-351013257
+        // Also, the ` | S` allows intellisense to not be dumbisense
         setState<K extends keyof S>(
-            state: ((prevState: Readonly<S>, props: P) => (Pick<S, K> & Partial<S>)) | (Pick<S, K> & Partial<S>),
+            state: ((prevState: Readonly<S>, props: P) => (Pick<S, K> | S)) | (Pick<S, K> | S),
             callback?: () => any
         ): void;
 
diff --git a/types/react/test/tsx.tsx b/types/react/test/tsx.tsx
index e43887c453..38d902c387 100644
--- a/types/react/test/tsx.tsx
+++ b/types/react/test/tsx.tsx
@@ -78,7 +78,8 @@ const StatelessComponentWithoutProps: React.SFC = (props) => {
     </React.Fragment>
 </div>;
 
-class Comp extends React.Component<{}, { foo: boolean, bar: boolean }> {
+// Below tests that setState() works properly for both regular and callback modes
+class SetStateTest extends React.Component<{}, { foo: boolean, bar: boolean }> {
     handleSomething = () => {
       this.setState({ foo: '' }); // $ExpectError
       this.setState({ foo: true });
@@ -94,3 +95,17 @@ class Comp extends React.Component<{}, { foo: boolean, bar: boolean }> {
       this.setState({ foo: true, bar: undefined}); // $ExpectError
     }
 }
+
+// Below tests that extended types for state work
+export abstract class SetStateTestForExtendsState<P, S extends { baseProp: string }> extends React.Component<P, S> {
+	foo() {
+		this.setState({ baseProp: 'foobar' });
+	}
+}
+
+// Below tests that & generic still works
+export abstract class SetStateTestForAndedState<P, S> extends React.Component<P, S & { baseProp: string }> {
+	foo() {
+		this.setState({ baseProp: 'foobar' });
+	}
+}
diff --git a/types/react/v15/index.d.ts b/types/react/v15/index.d.ts
index 7e036997fb..12b25439aa 100644
--- a/types/react/v15/index.d.ts
+++ b/types/react/v15/index.d.ts
@@ -284,8 +284,9 @@ declare namespace React {
 
         // We MUST keep setState() as a unified signature because it allows proper checking of the method return type.
         // See: https://github.com/DefinitelyTyped/DefinitelyTyped/issues/18365#issuecomment-351013257
+        // Also, the ` | S` allows intellisense to not be dumbisense
         setState<K extends keyof S>(
-            state: ((prevState: Readonly<S>, props: P) => (Pick<S, K> & Partial<S>)) | (Pick<S, K> & Partial<S>),
+            state: ((prevState: Readonly<S>, props: P) => (Pick<S, K> | S)) | (Pick<S, K> | S),
             callback?: () => any
         ): void;
 
diff --git a/types/react/v15/test/tsx.tsx b/types/react/v15/test/tsx.tsx
index 6f72279ff1..8afb75d9a8 100644
--- a/types/react/v15/test/tsx.tsx
+++ b/types/react/v15/test/tsx.tsx
@@ -64,7 +64,8 @@ const StatelessComponentWithoutProps: React.SFC = (props) => {
 };
 <StatelessComponentWithoutProps />;
 
-class Comp extends React.Component<{}, { foo: boolean, bar: boolean }> {
+// Below tests that setState() works properly for both regular and callback modes
+class SetStateTest extends React.Component<{}, { foo: boolean, bar: boolean }> {
     handleSomething = () => {
       this.setState({ foo: '' }); // $ExpectError
       this.setState({ foo: true });
@@ -80,3 +81,17 @@ class Comp extends React.Component<{}, { foo: boolean, bar: boolean }> {
       this.setState({ foo: true, bar: undefined}); // $ExpectError
     }
 }
+
+// Below tests that extended types for state work
+export abstract class SetStateTestForExtendsState<P, S extends { baseProp: string }> extends React.Component<P, S> {
+	foo() {
+		this.setState({ baseProp: 'foobar' });
+	}
+}
+
+// Below tests that & generic still works
+export abstract class SetStateTestForAndedState<P, S> extends React.Component<P, S & { baseProp: string }> {
+	foo() {
+		this.setState({ baseProp: 'foobar' });
+	}
+}