diff --git a/packages/redux-devtools-instrument/src/instrument.ts b/packages/redux-devtools-instrument/src/instrument.ts
index c6df45d0..a23f2c36 100644
--- a/packages/redux-devtools-instrument/src/instrument.ts
+++ b/packages/redux-devtools-instrument/src/instrument.ts
@@ -4,7 +4,6 @@ import isPlainObject from 'lodash/isPlainObject';
 import {
   Action,
   Observer,
-  PreloadedState,
   Reducer,
   Store,
   StoreEnhancer,
@@ -271,8 +270,8 @@ export const INIT_ACTION = { type: '@@INIT' };
 /**
  * Computes the next entry with exceptions catching.
  */
-function computeWithTryCatch<S, A extends Action<string>>(
-  reducer: Reducer<S, A>,
+function computeWithTryCatch<S, A extends Action<string>, PreloadedState>(
+  reducer: Reducer<S, A, PreloadedState>,
   action: A,
   state: S,
 ) {
@@ -301,8 +300,8 @@ function computeWithTryCatch<S, A extends Action<string>>(
 /**
  * Computes the next entry in the log by applying an action.
  */
-function computeNextEntry<S, A extends Action<string>>(
-  reducer: Reducer<S, A>,
+function computeNextEntry<S, A extends Action<string>, PreloadedState>(
+  reducer: Reducer<S, A, PreloadedState>,
   action: A,
   state: S,
   shouldCatchErrors: boolean | undefined,
@@ -316,10 +315,10 @@ function computeNextEntry<S, A extends Action<string>>(
 /**
  * Runs the reducer on invalidated actions to get a fresh computation log.
  */
-function recomputeStates<S, A extends Action<string>>(
+function recomputeStates<S, A extends Action<string>, PreloadedState>(
   computedStates: { state: S; error?: string }[],
   minInvalidatedStateIndex: number,
-  reducer: Reducer<S, A>,
+  reducer: Reducer<S, A, PreloadedState>,
   committedState: S,
   actionsById: { [actionId: number]: PerformAction<A> },
   stagedActionIds: number[],
@@ -413,11 +412,12 @@ export interface LiftedState<S, A extends Action<string>, MonitorState> {
 function liftReducerWith<
   S,
   A extends Action<string>,
+  PreloadedState,
   MonitorState,
   MonitorAction extends Action<string>,
 >(
-  reducer: Reducer<S, A>,
-  initialCommittedState: PreloadedState<S> | undefined,
+  reducer: Reducer<S, A, PreloadedState>,
+  initialCommittedState: S | PreloadedState | undefined,
   monitorReducer: Reducer<MonitorState, MonitorAction>,
   options: Options<S, A, MonitorState, MonitorAction>,
 ): Reducer<LiftedState<S, A, MonitorState>, LiftedAction<S, A, MonitorState>> {
@@ -575,7 +575,7 @@ function liftReducerWith<
 
       if (maxAge && stagedActionIds.length > maxAge) {
         // States must be recomputed before committing excess.
-        computedStates = recomputeStates<S, A>(
+        computedStates = recomputeStates<S, A, PreloadedState>(
           computedStates,
           minInvalidatedStateIndex,
           reducer,
@@ -872,6 +872,7 @@ export type EnhancedStore<S, A extends Action<string>, MonitorState> = Store<
 function unliftStore<
   S,
   A extends Action<string>,
+  PreloadedState,
   MonitorState,
   MonitorAction extends Action<string>,
   NextExt,
@@ -882,7 +883,9 @@ function unliftStore<
     LiftedAction<S, A, MonitorState>
   > &
     NextExt,
-  liftReducer: (r: Reducer<S, A>) => LiftedReducer<S, A, MonitorState>,
+  liftReducer: (
+    r: Reducer<S, A, PreloadedState>,
+  ) => LiftedReducer<S, A, MonitorState>,
   options: Options<S, A, MonitorState, MonitorAction>,
 ) {
   let lastDefinedState: S & NextStateExt;
@@ -924,7 +927,7 @@ function unliftStore<
     replaceReducer(nextReducer: Reducer<S & NextStateExt, A>) {
       liftedStore.replaceReducer(
         liftReducer(
-          nextReducer as unknown as Reducer<S, A>,
+          nextReducer as unknown as Reducer<S, A, PreloadedState>,
         ) as unknown as Reducer<
           LiftedState<S, A, MonitorState> & NextStateExt,
           LiftedAction<S, A, MonitorState>
@@ -1006,14 +1009,17 @@ export function instrument<
     );
   }
 
-  return <NextExt, NextStateExt>(
+  return <
+      NextExt extends NonNullable<unknown>,
+      NextStateExt extends NonNullable<unknown>,
+    >(
       createStore: StoreEnhancerStoreCreator<NextExt, NextStateExt>,
     ) =>
-    <S, A extends Action<string>>(
-      reducer: Reducer<S, A>,
-      initialState?: PreloadedState<S>,
+    <S, A extends Action<string>, PreloadedState>(
+      reducer: Reducer<S, A, PreloadedState>,
+      initialState?: PreloadedState | undefined,
     ) => {
-      function liftReducer(r: Reducer<S, A>) {
+      function liftReducer(r: Reducer<S, A, PreloadedState>) {
         if (typeof r !== 'function') {
           if (r && typeof (r as { default: unknown }).default === 'function') {
             throw new Error(
@@ -1025,7 +1031,13 @@ export function instrument<
           }
           throw new Error('Expected the reducer to be a function.');
         }
-        return liftReducerWith<S, A, MonitorState, MonitorAction>(
+        return liftReducerWith<
+          S,
+          A,
+          PreloadedState,
+          MonitorState,
+          MonitorAction
+        >(
           r,
           initialState,
           monitorReducer,
@@ -1057,12 +1069,17 @@ export function instrument<
       return unliftStore<
         S,
         A,
+        PreloadedState,
         MonitorState,
         MonitorAction,
         NextExt,
         NextStateExt
       >(
-        liftedStore,
+        liftedStore as Store<
+          LiftedState<S, A, MonitorState> & NextStateExt,
+          LiftedAction<S, A, MonitorState>
+        > &
+          NextExt,
         liftReducer,
         options as unknown as Options<S, A, MonitorState, MonitorAction>,
       );