diff --git a/types/iobroker/index.d.ts b/types/iobroker/index.d.ts
index 0ace066307..29ac96edb5 100644
--- a/types/iobroker/index.d.ts
+++ b/types/iobroker/index.d.ts
@@ -908,24 +908,24 @@ declare global {
             // tslint:disable:unified-signatures
             setState(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 callback?: SetStateCallback,
             ): void;
             setState(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 callback?: SetStateCallback,
             ): void;
             setState(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 options: unknown,
                 callback?: SetStateCallback,
             ): void;
             setState(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 options: unknown,
                 callback?: SetStateCallback,
@@ -933,41 +933,41 @@ declare global {
             /** Writes a value into the states DB. */
             setStateAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack?: boolean,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateCallback>>;
             setStateAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 options?: unknown,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateCallback>>;
             setStateAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 options: unknown,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateCallback>>;
             /** Writes a value into the states DB only if it has changed. */
             setStateChanged(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 callback?: SetStateChangedCallback,
             ): void;
             setStateChanged(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 callback?: SetStateChangedCallback,
             ): void;
             setStateChanged(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 options: unknown,
                 callback?: SetStateChangedCallback,
             ): void;
             setStateChanged(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 options: unknown,
                 callback?: SetStateChangedCallback,
@@ -975,41 +975,41 @@ declare global {
             /** Writes a value into the states DB only if it has changed. */
             setStateChangedAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack?: boolean,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateChangedCallback>>;
             setStateChangedAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 options?: unknown,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateChangedCallback>>;
             setStateChangedAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 options: unknown,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateChangedCallback>>;
             /** Writes a value (which might not belong to this adapter) into the states DB. */
             setForeignState(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 callback?: SetStateCallback,
             ): void;
             setForeignState(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 callback?: SetStateCallback,
             ): void;
             setForeignState(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 options: unknown,
                 callback?: SetStateCallback,
             ): void;
             setForeignState(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 options: unknown,
                 callback?: SetStateCallback,
@@ -1017,41 +1017,41 @@ declare global {
             /** Writes a value (which might not belong to this adapter) into the states DB. */
             setForeignStateAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack?: boolean,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateCallback>>;
             setForeignStateAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 options?: unknown,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateCallback>>;
             setForeignStateAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 options: unknown,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateCallback>>;
             /** Writes a value (which might not belong to this adapter) into the states DB only if it has changed. */
             setForeignStateChanged(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 callback?: SetStateChangedCallback,
             ): void;
             setForeignStateChanged(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 callback?: SetStateChangedCallback,
             ): void;
             setForeignStateChanged(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 options: unknown,
                 callback?: SetStateChangedCallback,
             ): void;
             setForeignStateChanged(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 options: unknown,
                 callback?: SetStateChangedCallback,
@@ -1059,17 +1059,17 @@ declare global {
             /** Writes a value (which might not belong to this adapter) into the states DB only if it has changed. */
             setForeignStateChangedAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack?: boolean,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateChangedCallback>>;
             setForeignStateChangedAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 options?: unknown,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateChangedCallback>>;
             setForeignStateChangedAsync(
                 id: string,
-                state: string | number | boolean | State | SettableState,
+                state: string | number | boolean | State | SettableState | null,
                 ack: boolean,
                 options: unknown,
             ): Promise<NonNullCallbackReturnTypeOf<SetStateChangedCallback>>;
diff --git a/types/iobroker/iobroker-tests.ts b/types/iobroker/iobroker-tests.ts
index ce524567e9..6e3c943a68 100644
--- a/types/iobroker/iobroker-tests.ts
+++ b/types/iobroker/iobroker-tests.ts
@@ -400,3 +400,13 @@ const folderObj: ioBroker.FolderObject = {
 // Repro from https://github.com/ioBroker/ioBroker.js-controller/issues/782
 // $ExpectError
 adapter.setState("id", {ack: false});
+
+// null is a valid state value
+adapter.setState("id", null);
+adapter.setForeignState("id", null);
+adapter.setStateAsync("id", null);
+adapter.setForeignStateAsync("id", null);
+adapter.setStateChanged("id", null);
+adapter.setForeignStateChanged("id", null);
+adapter.setStateChangedAsync("id", null);
+adapter.setForeignStateChangedAsync("id", null);