diff --git a/apps/browser/src/platform/state/derived-state-interactions.spec.ts b/apps/browser/src/platform/state/derived-state-interactions.spec.ts
index 058b03b39d1..5bfa76a6725 100644
--- a/apps/browser/src/platform/state/derived-state-interactions.spec.ts
+++ b/apps/browser/src/platform/state/derived-state-interactions.spec.ts
@@ -3,7 +3,7 @@
  * @jest-environment ../../libs/shared/test.environment.ts
  */
 
-import { OperatorFunction, Subject, firstValueFrom, identity } from "rxjs";
+import { Subject, firstValueFrom, identity } from "rxjs";
 
 import { DeriveDefinition } from "@bitwarden/common/platform/state";
 // eslint-disable-next-line import/no-restricted-paths -- needed to define a derive definition
@@ -41,11 +41,7 @@ describe("foreground background derived state interactions", () => {
     parentState$ = new Subject<string>();
 
     background = new BackgroundDerivedState(parentState$, deriveDefinition, portName, {});
-    foreground = new ForegroundDerivedState<Date>(
-      deriveDefinition,
-      portName,
-      identity as OperatorFunction<string, Date>,
-    );
+    foreground = new ForegroundDerivedState<Date>(deriveDefinition, portName, identity);
   });
 
   afterEach(() => {
diff --git a/apps/browser/src/platform/state/foreground-derived-state.provider.ts b/apps/browser/src/platform/state/foreground-derived-state.provider.ts
index bcf0a0158a8..beb859e84d6 100644
--- a/apps/browser/src/platform/state/foreground-derived-state.provider.ts
+++ b/apps/browser/src/platform/state/foreground-derived-state.provider.ts
@@ -1,4 +1,4 @@
-import { Observable, OperatorFunction } from "rxjs";
+import { MonoTypeOperatorFunction, Observable } from "rxjs";
 
 import { DeriveDefinition, DerivedState } from "@bitwarden/common/platform/state";
 // eslint-disable-next-line import/no-restricted-paths -- extending this class for this client
@@ -8,7 +8,7 @@ import { DerivedStateDependencies } from "@bitwarden/common/src/types/state";
 import { ForegroundDerivedState } from "./foreground-derived-state";
 
 export class ForegroundDerivedStateProvider extends DefaultDerivedStateProvider {
-  constructor(private pipeCustomizer: OperatorFunction<unknown, unknown>) {
+  constructor(private pipeCustomizer: MonoTypeOperatorFunction<unknown>) {
     super();
   }
   override buildDerivedState<TFrom, TTo, TDeps extends DerivedStateDependencies>(
@@ -19,7 +19,7 @@ export class ForegroundDerivedStateProvider extends DefaultDerivedStateProvider
     return new ForegroundDerivedState(
       deriveDefinition,
       deriveDefinition.buildCacheKey(),
-      this.pipeCustomizer as OperatorFunction<TFrom, TTo>,
+      this.pipeCustomizer as MonoTypeOperatorFunction<TTo>,
     );
   }
 }
diff --git a/apps/browser/src/platform/state/foreground-derived-state.spec.ts b/apps/browser/src/platform/state/foreground-derived-state.spec.ts
index f6e83156d9a..5c3eabd9d8f 100644
--- a/apps/browser/src/platform/state/foreground-derived-state.spec.ts
+++ b/apps/browser/src/platform/state/foreground-derived-state.spec.ts
@@ -1,5 +1,5 @@
 import { awaitAsync } from "@bitwarden/common/../spec";
-import { OperatorFunction, identity } from "rxjs";
+import { identity } from "rxjs";
 
 import { DeriveDefinition } from "@bitwarden/common/platform/state";
 // eslint-disable-next-line import/no-restricted-paths -- needed to define a derive definition
@@ -22,11 +22,7 @@ describe("ForegroundDerivedState", () => {
 
   beforeEach(() => {
     mockPorts();
-    sut = new ForegroundDerivedState<Date>(
-      deriveDefinition,
-      portName,
-      identity as OperatorFunction<unknown, Date>,
-    );
+    sut = new ForegroundDerivedState<Date>(deriveDefinition, portName, identity);
   });
 
   afterEach(() => {
diff --git a/apps/browser/src/platform/state/foreground-derived-state.ts b/apps/browser/src/platform/state/foreground-derived-state.ts
index 79961b1af00..b605b8e71b5 100644
--- a/apps/browser/src/platform/state/foreground-derived-state.ts
+++ b/apps/browser/src/platform/state/foreground-derived-state.ts
@@ -1,6 +1,6 @@
 import {
+  MonoTypeOperatorFunction,
   Observable,
-  OperatorFunction,
   ReplaySubject,
   defer,
   filter,
@@ -28,7 +28,7 @@ export class ForegroundDerivedState<TTo> implements DerivedState<TTo> {
   constructor(
     private deriveDefinition: DeriveDefinition<unknown, TTo, DerivedStateDependencies>,
     private portName: string,
-    private pipeCustomizer: OperatorFunction<unknown, TTo>,
+    private pipeCustomizer: MonoTypeOperatorFunction<TTo>,
   ) {
     const latestValueFromPort$ = (port: chrome.runtime.Port) => {
       return fromChromeEvent(port.onMessage).pipe(