diff --git a/docs/api/createEntityAdapter.mdx b/docs/api/createEntityAdapter.mdx
index 0cfee25b9e..10eb7afbe1 100644
--- a/docs/api/createEntityAdapter.mdx
+++ b/docs/api/createEntityAdapter.mdx
@@ -118,19 +118,11 @@ export type Comparer<T> = (a: T, b: T) => number
 
 export type IdSelector<T> = (model: T) => EntityId
 
-export interface DictionaryNum<T> {
-  [id: number]: T | undefined
-}
-
-export interface Dictionary<T> extends DictionaryNum<T> {
-  [id: string]: T | undefined
-}
-
 export type Update<T> = { id: EntityId; changes: Partial<T> }
 
 export interface EntityState<T> {
   ids: EntityId[]
-  entities: Dictionary<T>
+  entities: Record<EntityId, T>
 }
 
 export interface EntityDefinition<T> {
@@ -183,7 +175,7 @@ export interface EntityStateAdapter<T> {
 
 export interface EntitySelectors<T, V> {
   selectIds: (state: V) => EntityId[]
-  selectEntities: (state: V) => Dictionary<T>
+  selectEntities: (state: V) => Record<EntityId, T>
   selectAll: (state: V) => T[]
   selectTotal: (state: V) => number
   selectById: (state: V, id: EntityId) => T | undefined
@@ -228,7 +220,6 @@ All three options will insert _new_ entities into the list. However they differ
 
 :::
 
-
 Each method has a signature that looks like:
 
 ```ts no-transpile
@@ -358,12 +349,8 @@ const booksSlice = createSlice({
   },
 })
 
-const {
-  bookAdded,
-  booksLoading,
-  booksReceived,
-  bookUpdated,
-} = booksSlice.actions
+const { bookAdded, booksLoading, booksReceived, bookUpdated } =
+  booksSlice.actions
 
 const store = configureStore({
   reducer: {
diff --git a/packages/toolkit/src/entities/entity_state.ts b/packages/toolkit/src/entities/entity_state.ts
index 8a9c6a895c..62ab918442 100644
--- a/packages/toolkit/src/entities/entity_state.ts
+++ b/packages/toolkit/src/entities/entity_state.ts
@@ -6,7 +6,7 @@ export function getInitialEntityState<T, Id extends EntityId>(): EntityState<
 > {
   return {
     ids: [],
-    entities: {},
+    entities: {} as Record<Id, T>,
   }
 }
 
diff --git a/packages/toolkit/src/entities/index.ts b/packages/toolkit/src/entities/index.ts
index 9e2292a24c..e258527474 100644
--- a/packages/toolkit/src/entities/index.ts
+++ b/packages/toolkit/src/entities/index.ts
@@ -1,6 +1,5 @@
 export { createEntityAdapter } from './create_adapter'
 export type {
-  Dictionary,
   EntityState,
   EntityAdapter,
   Update,
diff --git a/packages/toolkit/src/entities/models.ts b/packages/toolkit/src/entities/models.ts
index d20db1c5de..55e5a9779a 100644
--- a/packages/toolkit/src/entities/models.ts
+++ b/packages/toolkit/src/entities/models.ts
@@ -1,5 +1,6 @@
+import type { UncheckedIndexedAccess } from '../uncheckedindexed'
 import type { PayloadAction } from '../createAction'
-import type { IsAny } from '../tsHelpers'
+import type { CastAny, Id as Compute } from '../tsHelpers'
 
 /**
  * @public
@@ -16,11 +17,6 @@ export type Comparer<T> = (a: T, b: T) => number
  */
 export type IdSelector<T, Id extends EntityId> = (model: T) => Id
 
-/**
- * @public
- */
-export type Dictionary<T, Id extends EntityId> = Partial<Record<Id, T>>
-
 /**
  * @public
  */
@@ -31,7 +27,7 @@ export type Update<T, Id extends EntityId> = { id: Id; changes: Partial<T> }
  */
 export interface EntityState<T, Id extends EntityId> {
   ids: Id[]
-  entities: Dictionary<T, Id>
+  entities: Record<Id, T>
 }
 
 /**
@@ -42,10 +38,9 @@ export interface EntityDefinition<T, Id extends EntityId> {
   sortComparer: false | Comparer<T>
 }
 
-export type PreventAny<S, T, Id extends EntityId> = IsAny<
+export type PreventAny<S, T, Id extends EntityId> = CastAny<
   S,
-  EntityState<T, Id>,
-  S
+  EntityState<T, Id>
 >
 
 /**
@@ -157,10 +152,10 @@ export interface EntityStateAdapter<T, Id extends EntityId> {
  */
 export interface EntitySelectors<T, V, Id extends EntityId> {
   selectIds: (state: V) => Id[]
-  selectEntities: (state: V) => Dictionary<T, Id>
+  selectEntities: (state: V) => Record<Id, T>
   selectAll: (state: V) => T[]
   selectTotal: (state: V) => number
-  selectById: (state: V, id: Id) => T | undefined
+  selectById: (state: V, id: Id) => Compute<UncheckedIndexedAccess<T>>
 }
 
 /**
diff --git a/packages/toolkit/src/entities/sorted_state_adapter.ts b/packages/toolkit/src/entities/sorted_state_adapter.ts
index 96bb75da4a..7d73513671 100644
--- a/packages/toolkit/src/entities/sorted_state_adapter.ts
+++ b/packages/toolkit/src/entities/sorted_state_adapter.ts
@@ -61,7 +61,7 @@ export function createSortedStateAdapter<T, Id extends EntityId>(
     state: R
   ): void {
     newEntities = ensureEntitiesArray(newEntities)
-    state.entities = {}
+    state.entities = {} as Record<Id, T>
     state.ids = []
 
     addManyMutably(newEntities, state)
diff --git a/packages/toolkit/src/entities/state_selectors.ts b/packages/toolkit/src/entities/state_selectors.ts
index 92a0f82378..a647d4f248 100644
--- a/packages/toolkit/src/entities/state_selectors.ts
+++ b/packages/toolkit/src/entities/state_selectors.ts
@@ -1,11 +1,6 @@
 import type { Selector } from 'reselect'
 import { createDraftSafeSelector } from '../createDraftSafeSelector'
-import type {
-  EntityState,
-  EntitySelectors,
-  Dictionary,
-  EntityId,
-} from './models'
+import type { EntityState, EntitySelectors, EntityId } from './models'
 
 export function createSelectorsFactory<T, Id extends EntityId>() {
   function getSelectors(): EntitySelectors<T, EntityState<T, Id>, Id>
@@ -27,7 +22,7 @@ export function createSelectorsFactory<T, Id extends EntityId>() {
 
     const selectId = (_: unknown, id: Id) => id
 
-    const selectById = (entities: Dictionary<T, Id>, id: Id) => entities[id]
+    const selectById = (entities: Record<Id, T>, id: Id) => entities[id]
 
     const selectTotal = createDraftSafeSelector(selectIds, (ids) => ids.length)
 
diff --git a/packages/toolkit/src/entities/unsorted_state_adapter.ts b/packages/toolkit/src/entities/unsorted_state_adapter.ts
index 9c3295dc43..77697e1618 100644
--- a/packages/toolkit/src/entities/unsorted_state_adapter.ts
+++ b/packages/toolkit/src/entities/unsorted_state_adapter.ts
@@ -67,7 +67,7 @@ export function createUnsortedStateAdapter<T, Id extends EntityId>(
     newEntities = ensureEntitiesArray(newEntities)
 
     state.ids = []
-    state.entities = {}
+    state.entities = {} as Record<Id, T>
 
     addManyMutably(newEntities, state)
   }
diff --git a/packages/toolkit/src/index.ts b/packages/toolkit/src/index.ts
index f30024161f..48ea776850 100644
--- a/packages/toolkit/src/index.ts
+++ b/packages/toolkit/src/index.ts
@@ -105,7 +105,6 @@ export { Tuple } from './utils'
 
 export { createEntityAdapter } from './entities/create_adapter'
 export type {
-  Dictionary,
   EntityState,
   EntityAdapter,
   EntitySelectors,
diff --git a/packages/toolkit/src/tsHelpers.ts b/packages/toolkit/src/tsHelpers.ts
index d08ed5dda0..f0ed92a6e1 100644
--- a/packages/toolkit/src/tsHelpers.ts
+++ b/packages/toolkit/src/tsHelpers.ts
@@ -18,6 +18,8 @@ export type IsAny<T, True, False = never> =
   // test if we are going the left AND right path in the condition
   true | false extends (T extends never ? true : false) ? True : False
 
+export type CastAny<T, CastTo> = IsAny<T, CastTo, T>
+
 /**
  * return True if T is `unknown`, otherwise return False
  * taken from /~https://github.com/joonhocho/tsdef
diff --git a/packages/toolkit/src/uncheckedindexed.ts b/packages/toolkit/src/uncheckedindexed.ts
new file mode 100644
index 0000000000..628ff5dc43
--- /dev/null
+++ b/packages/toolkit/src/uncheckedindexed.ts
@@ -0,0 +1,16 @@
+// inlined from /~https://github.com/EskiMojo14/uncheckedindexed
+// relies on remaining as a TS file, not .d.ts
+type IfMaybeUndefined<T, True, False> = [undefined] extends [T] ? True : False
+
+const testAccess = ({} as Record<string, 0>).a
+
+export type IfUncheckedIndexedAccess<True, False> = IfMaybeUndefined<
+  typeof testAccess,
+  True,
+  False
+>
+
+export type UncheckedIndexedAccess<T> = IfUncheckedIndexedAccess<
+  T | undefined,
+  T
+>
diff --git a/packages/toolkit/tsup.config.ts b/packages/toolkit/tsup.config.ts
index d4d9219086..4a3aa994fb 100644
--- a/packages/toolkit/tsup.config.ts
+++ b/packages/toolkit/tsup.config.ts
@@ -203,6 +203,15 @@ export default defineConfig((options) => {
             if (format === 'cjs' && name === 'production.min') {
               writeCommonJSEntry(outputFolder, prefix)
             } else if (generateTypedefs) {
+              if (folder === '') {
+                // we need to delete the declaration file and replace it with the original source file
+                fs.rmSync(path.join(outputFolder, 'uncheckedindexed.d.ts'))
+
+                fs.copyFileSync(
+                  'src/uncheckedindexed.ts',
+                  path.join(outputFolder, 'uncheckedindexed.ts')
+                )
+              }
               // TODO Copy/generate `.d.mts` files?
               // const inputTypedefsFile = `${outputFilename}.d.ts`
               // const outputTypedefsFile = `${outputFilename}.d.mts`