diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 0b67afefbb9d8..7f693faac9495 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -17729,7 +17729,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         // eagerly using the constraint type of 'this' at the given location.
         if (isGenericIndexType(indexType) || (accessNode && accessNode.kind !== SyntaxKind.IndexedAccessType ?
             isGenericTupleType(objectType) && !indexTypeLessThan(indexType, objectType.target.fixedLength) :
-            isGenericObjectType(objectType) && !(isTupleType(objectType) && indexTypeLessThan(indexType, objectType.target.fixedLength)) || isGenericReducibleType(objectType))) {
+            isGenericObjectType(objectType) && !(isTupleType(objectType) && indexTypeLessThan(indexType, objectType.target.fixedLength)) || !(accessFlags & AccessFlags.Writing) && isGenericReducibleType(objectType))) {
             if (objectType.flags & TypeFlags.AnyOrUnknown) {
                 return objectType;
             }
diff --git a/tests/baselines/reference/correlatedUnions.js b/tests/baselines/reference/correlatedUnions.js
index 5335811054601..9a8d000bb6aac 100644
--- a/tests/baselines/reference/correlatedUnions.js
+++ b/tests/baselines/reference/correlatedUnions.js
@@ -301,6 +301,79 @@ function getValueConcrete<K extends keyof Foo1>(
 ): Foo1[K] | undefined {
   return o[k];
 }
+
+// repro from https://github.com/microsoft/TypeScript/issues/54680
+
+type A_54680 = {
+  type: "A";
+  value: string;
+};
+
+type B_54680 = {
+  type: "B";
+  value: number;
+};
+
+type Message_54680 = A_54680 | B_54680;
+
+function handle_54680_1<M extends Message_54680>(callbacks: {
+  [K in M["type"]]: (msg: Extract<M, { type: K }>["value"]) => unknown;
+}) {
+  window.addEventListener("message", (event) => {
+    const msg = event.data as M;
+    callbacks[msg.type as keyof typeof callbacks](msg.value);
+  });
+}
+
+function handle_54680_2<M extends Message_54680>(callbacks: {
+  [K in M["type"]]: (msg: (M & { type: K })["value"]) => unknown;
+}) {
+  window.addEventListener("message", (event) => {
+    const msg = event.data as M;
+    callbacks[msg.type as keyof typeof callbacks](msg.value);
+  });
+}
+
+// repro from https://github.com/microsoft/TypeScript/issues/54834
+
+type NumericLiteral_54834 = {
+  value: number;
+  type: "NumericLiteral";
+};
+type StringLiteral_54834 = {
+  value: string;
+  type: "StringLiteral";
+};
+type Identifier_54834 = {
+  name: string;
+  type: "Identifier";
+};
+type CallExpression_54834 = {
+  name: string;
+  arguments: DropbearNode_54834[];
+  type: "CallExpression";
+};
+
+type DropbearNode_54834 =
+  | NumericLiteral_54834
+  | StringLiteral_54834
+  | Identifier_54834
+  | CallExpression_54834;
+
+type TypeMap_54834 = {
+  [K in DropbearNode_54834["type"]]: Extract<DropbearNode_54834, { type: K }>;
+};
+
+type Visitor_54834 = {
+  [K in keyof TypeMap_54834]: (node: Readonly<TypeMap_54834[K]>) => void;
+};
+
+function visitNode_54834<K extends keyof TypeMap_54834>(
+  node: Readonly<TypeMap_54834[K]>,
+  v: Visitor_54834
+) {
+  v[node.type](node);
+}
 
 
 //// [correlatedUnions.js]
@@ -433,6 +506,21 @@ function getConfigOrDefault(userConfig, key, defaultValue) {
 function getValueConcrete(o, k) {
     return o[k];
 }
+function handle_54680_1(callbacks) {
+    window.addEventListener("message", function (event) {
+        var msg = event.data;
+        callbacks[msg.type](msg.value);
+    });
+}
+function handle_54680_2(callbacks) {
+    window.addEventListener("message", function (event) {
+        var msg = event.data;
+        callbacks[msg.type](msg.value);
+    });
+}
+function visitNode_54834(node, v) {
+    v[node.type](node);
+}
 
 
 //// [correlatedUnions.d.ts]
@@ -613,3 +701,49 @@ type Foo1 = {
     y: string;
 };
 declare function getValueConcrete<K extends keyof Foo1>(o: Partial<Foo1>, k: K): Foo1[K] | undefined;
+type A_54680 = {
+    type: "A";
+    value: string;
+};
+type B_54680 = {
+    type: "B";
+    value: number;
+};
+type Message_54680 = A_54680 | B_54680;
+declare function handle_54680_1<M extends Message_54680>(callbacks: {
+    [K in M["type"]]: (msg: Extract<M, {
+        type: K;
+    }>["value"]) => unknown;
+}): void;
+declare function handle_54680_2<M extends Message_54680>(callbacks: {
+    [K in M["type"]]: (msg: (M & {
+        type: K;
+    })["value"]) => unknown;
+}): void;
+type NumericLiteral_54834 = {
+    value: number;
+    type: "NumericLiteral";
+};
+type StringLiteral_54834 = {
+    value: string;
+    type: "StringLiteral";
+};
+type Identifier_54834 = {
+    name: string;
+    type: "Identifier";
+};
+type CallExpression_54834 = {
+    name: string;
+    arguments: DropbearNode_54834[];
+    type: "CallExpression";
+};
+type DropbearNode_54834 = NumericLiteral_54834 | StringLiteral_54834 | Identifier_54834 | CallExpression_54834;
+type TypeMap_54834 = {
+    [K in DropbearNode_54834["type"]]: Extract<DropbearNode_54834, {
+        type: K;
+    }>;
+};
+type Visitor_54834 = {
+    [K in keyof TypeMap_54834]: (node: Readonly<TypeMap_54834[K]>) => void;
+};
+declare function visitNode_54834<K extends keyof TypeMap_54834>(node: Readonly<TypeMap_54834[K]>, v: Visitor_54834): void;
diff --git a/tests/baselines/reference/correlatedUnions.symbols b/tests/baselines/reference/correlatedUnions.symbols
index bf5fe9d678045..b4170c93b39c2 100644
--- a/tests/baselines/reference/correlatedUnions.symbols
+++ b/tests/baselines/reference/correlatedUnions.symbols
@@ -1016,3 +1016,227 @@ function getValueConcrete<K extends keyof Foo1>(
 >k : Symbol(k, Decl(correlatedUnions.ts, 295, 19))
 }
 
+// repro from https://github.com/microsoft/TypeScript/issues/54680
+
+type A_54680 = {
+>A_54680 : Symbol(A_54680, Decl(correlatedUnions.ts, 299, 1))
+
+  type: "A";
+>type : Symbol(type, Decl(correlatedUnions.ts, 303, 16))
+
+  value: string;
+>value : Symbol(value, Decl(correlatedUnions.ts, 304, 12))
+
+};
+
+type B_54680 = {
+>B_54680 : Symbol(B_54680, Decl(correlatedUnions.ts, 306, 2))
+
+  type: "B";
+>type : Symbol(type, Decl(correlatedUnions.ts, 308, 16))
+
+  value: number;
+>value : Symbol(value, Decl(correlatedUnions.ts, 309, 12))
+
+};
+
+type Message_54680 = A_54680 | B_54680;
+>Message_54680 : Symbol(Message_54680, Decl(correlatedUnions.ts, 311, 2))
+>A_54680 : Symbol(A_54680, Decl(correlatedUnions.ts, 299, 1))
+>B_54680 : Symbol(B_54680, Decl(correlatedUnions.ts, 306, 2))
+
+function handle_54680_1<M extends Message_54680>(callbacks: {
+>handle_54680_1 : Symbol(handle_54680_1, Decl(correlatedUnions.ts, 313, 39))
+>M : Symbol(M, Decl(correlatedUnions.ts, 315, 24))
+>Message_54680 : Symbol(Message_54680, Decl(correlatedUnions.ts, 311, 2))
+>callbacks : Symbol(callbacks, Decl(correlatedUnions.ts, 315, 49))
+
+  [K in M["type"]]: (msg: Extract<M, { type: K }>["value"]) => unknown;
+>K : Symbol(K, Decl(correlatedUnions.ts, 316, 3))
+>M : Symbol(M, Decl(correlatedUnions.ts, 315, 24))
+>msg : Symbol(msg, Decl(correlatedUnions.ts, 316, 21))
+>Extract : Symbol(Extract, Decl(lib.es5.d.ts, --, --))
+>M : Symbol(M, Decl(correlatedUnions.ts, 315, 24))
+>type : Symbol(type, Decl(correlatedUnions.ts, 316, 38))
+>K : Symbol(K, Decl(correlatedUnions.ts, 316, 3))
+
+}) {
+  window.addEventListener("message", (event) => {
+>window.addEventListener : Symbol(addEventListener, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
+>window : Symbol(window, Decl(lib.dom.d.ts, --, --))
+>addEventListener : Symbol(addEventListener, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
+>event : Symbol(event, Decl(correlatedUnions.ts, 318, 38))
+
+    const msg = event.data as M;
+>msg : Symbol(msg, Decl(correlatedUnions.ts, 319, 9))
+>event.data : Symbol(MessageEvent.data, Decl(lib.dom.d.ts, --, --))
+>event : Symbol(event, Decl(correlatedUnions.ts, 318, 38))
+>data : Symbol(MessageEvent.data, Decl(lib.dom.d.ts, --, --))
+>M : Symbol(M, Decl(correlatedUnions.ts, 315, 24))
+
+    callbacks[msg.type as keyof typeof callbacks](msg.value);
+>callbacks : Symbol(callbacks, Decl(correlatedUnions.ts, 315, 49))
+>msg.type : Symbol(type, Decl(correlatedUnions.ts, 303, 16), Decl(correlatedUnions.ts, 308, 16))
+>msg : Symbol(msg, Decl(correlatedUnions.ts, 319, 9))
+>type : Symbol(type, Decl(correlatedUnions.ts, 303, 16), Decl(correlatedUnions.ts, 308, 16))
+>callbacks : Symbol(callbacks, Decl(correlatedUnions.ts, 315, 49))
+>msg.value : Symbol(value, Decl(correlatedUnions.ts, 304, 12), Decl(correlatedUnions.ts, 309, 12))
+>msg : Symbol(msg, Decl(correlatedUnions.ts, 319, 9))
+>value : Symbol(value, Decl(correlatedUnions.ts, 304, 12), Decl(correlatedUnions.ts, 309, 12))
+
+  });
+}
+
+function handle_54680_2<M extends Message_54680>(callbacks: {
+>handle_54680_2 : Symbol(handle_54680_2, Decl(correlatedUnions.ts, 322, 1))
+>M : Symbol(M, Decl(correlatedUnions.ts, 324, 24))
+>Message_54680 : Symbol(Message_54680, Decl(correlatedUnions.ts, 311, 2))
+>callbacks : Symbol(callbacks, Decl(correlatedUnions.ts, 324, 49))
+
+  [K in M["type"]]: (msg: (M & { type: K })["value"]) => unknown;
+>K : Symbol(K, Decl(correlatedUnions.ts, 325, 3))
+>M : Symbol(M, Decl(correlatedUnions.ts, 324, 24))
+>msg : Symbol(msg, Decl(correlatedUnions.ts, 325, 21))
+>M : Symbol(M, Decl(correlatedUnions.ts, 324, 24))
+>type : Symbol(type, Decl(correlatedUnions.ts, 325, 32))
+>K : Symbol(K, Decl(correlatedUnions.ts, 325, 3))
+
+}) {
+  window.addEventListener("message", (event) => {
+>window.addEventListener : Symbol(addEventListener, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
+>window : Symbol(window, Decl(lib.dom.d.ts, --, --))
+>addEventListener : Symbol(addEventListener, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
+>event : Symbol(event, Decl(correlatedUnions.ts, 327, 38))
+
+    const msg = event.data as M;
+>msg : Symbol(msg, Decl(correlatedUnions.ts, 328, 9))
+>event.data : Symbol(MessageEvent.data, Decl(lib.dom.d.ts, --, --))
+>event : Symbol(event, Decl(correlatedUnions.ts, 327, 38))
+>data : Symbol(MessageEvent.data, Decl(lib.dom.d.ts, --, --))
+>M : Symbol(M, Decl(correlatedUnions.ts, 324, 24))
+
+    callbacks[msg.type as keyof typeof callbacks](msg.value);
+>callbacks : Symbol(callbacks, Decl(correlatedUnions.ts, 324, 49))
+>msg.type : Symbol(type, Decl(correlatedUnions.ts, 303, 16), Decl(correlatedUnions.ts, 308, 16))
+>msg : Symbol(msg, Decl(correlatedUnions.ts, 328, 9))
+>type : Symbol(type, Decl(correlatedUnions.ts, 303, 16), Decl(correlatedUnions.ts, 308, 16))
+>callbacks : Symbol(callbacks, Decl(correlatedUnions.ts, 324, 49))
+>msg.value : Symbol(value, Decl(correlatedUnions.ts, 304, 12), Decl(correlatedUnions.ts, 309, 12))
+>msg : Symbol(msg, Decl(correlatedUnions.ts, 328, 9))
+>value : Symbol(value, Decl(correlatedUnions.ts, 304, 12), Decl(correlatedUnions.ts, 309, 12))
+
+  });
+}
+
+// repro from https://github.com/microsoft/TypeScript/issues/54834
+
+type NumericLiteral_54834 = {
+>NumericLiteral_54834 : Symbol(NumericLiteral_54834, Decl(correlatedUnions.ts, 331, 1))
+
+  value: number;
+>value : Symbol(value, Decl(correlatedUnions.ts, 335, 29))
+
+  type: "NumericLiteral";
+>type : Symbol(type, Decl(correlatedUnions.ts, 336, 16))
+
+};
+type StringLiteral_54834 = {
+>StringLiteral_54834 : Symbol(StringLiteral_54834, Decl(correlatedUnions.ts, 338, 2))
+
+  value: string;
+>value : Symbol(value, Decl(correlatedUnions.ts, 339, 28))
+
+  type: "StringLiteral";
+>type : Symbol(type, Decl(correlatedUnions.ts, 340, 16))
+
+};
+type Identifier_54834 = {
+>Identifier_54834 : Symbol(Identifier_54834, Decl(correlatedUnions.ts, 342, 2))
+
+  name: string;
+>name : Symbol(name, Decl(correlatedUnions.ts, 343, 25))
+
+  type: "Identifier";
+>type : Symbol(type, Decl(correlatedUnions.ts, 344, 15))
+
+};
+type CallExpression_54834 = {
+>CallExpression_54834 : Symbol(CallExpression_54834, Decl(correlatedUnions.ts, 346, 2))
+
+  name: string;
+>name : Symbol(name, Decl(correlatedUnions.ts, 347, 29))
+
+  arguments: DropbearNode_54834[];
+>arguments : Symbol(arguments, Decl(correlatedUnions.ts, 348, 15))
+>DropbearNode_54834 : Symbol(DropbearNode_54834, Decl(correlatedUnions.ts, 351, 2))
+
+  type: "CallExpression";
+>type : Symbol(type, Decl(correlatedUnions.ts, 349, 34))
+
+};
+
+type DropbearNode_54834 =
+>DropbearNode_54834 : Symbol(DropbearNode_54834, Decl(correlatedUnions.ts, 351, 2))
+
+  | NumericLiteral_54834
+>NumericLiteral_54834 : Symbol(NumericLiteral_54834, Decl(correlatedUnions.ts, 331, 1))
+
+  | StringLiteral_54834
+>StringLiteral_54834 : Symbol(StringLiteral_54834, Decl(correlatedUnions.ts, 338, 2))
+
+  | Identifier_54834
+>Identifier_54834 : Symbol(Identifier_54834, Decl(correlatedUnions.ts, 342, 2))
+
+  | CallExpression_54834;
+>CallExpression_54834 : Symbol(CallExpression_54834, Decl(correlatedUnions.ts, 346, 2))
+
+type TypeMap_54834 = {
+>TypeMap_54834 : Symbol(TypeMap_54834, Decl(correlatedUnions.ts, 357, 25))
+
+  [K in DropbearNode_54834["type"]]: Extract<DropbearNode_54834, { type: K }>;
+>K : Symbol(K, Decl(correlatedUnions.ts, 360, 3))
+>DropbearNode_54834 : Symbol(DropbearNode_54834, Decl(correlatedUnions.ts, 351, 2))
+>Extract : Symbol(Extract, Decl(lib.es5.d.ts, --, --))
+>DropbearNode_54834 : Symbol(DropbearNode_54834, Decl(correlatedUnions.ts, 351, 2))
+>type : Symbol(type, Decl(correlatedUnions.ts, 360, 66))
+>K : Symbol(K, Decl(correlatedUnions.ts, 360, 3))
+
+};
+
+type Visitor_54834 = {
+>Visitor_54834 : Symbol(Visitor_54834, Decl(correlatedUnions.ts, 361, 2))
+
+  [K in keyof TypeMap_54834]: (node: Readonly<TypeMap_54834[K]>) => void;
+>K : Symbol(K, Decl(correlatedUnions.ts, 364, 3))
+>TypeMap_54834 : Symbol(TypeMap_54834, Decl(correlatedUnions.ts, 357, 25))
+>node : Symbol(node, Decl(correlatedUnions.ts, 364, 31))
+>Readonly : Symbol(Readonly, Decl(lib.es5.d.ts, --, --))
+>TypeMap_54834 : Symbol(TypeMap_54834, Decl(correlatedUnions.ts, 357, 25))
+>K : Symbol(K, Decl(correlatedUnions.ts, 364, 3))
+
+};
+
+function visitNode_54834<K extends keyof TypeMap_54834>(
+>visitNode_54834 : Symbol(visitNode_54834, Decl(correlatedUnions.ts, 365, 2))
+>K : Symbol(K, Decl(correlatedUnions.ts, 367, 25))
+>TypeMap_54834 : Symbol(TypeMap_54834, Decl(correlatedUnions.ts, 357, 25))
+
+  node: Readonly<TypeMap_54834[K]>,
+>node : Symbol(node, Decl(correlatedUnions.ts, 367, 56))
+>Readonly : Symbol(Readonly, Decl(lib.es5.d.ts, --, --))
+>TypeMap_54834 : Symbol(TypeMap_54834, Decl(correlatedUnions.ts, 357, 25))
+>K : Symbol(K, Decl(correlatedUnions.ts, 367, 25))
+
+  v: Visitor_54834
+>v : Symbol(v, Decl(correlatedUnions.ts, 368, 35))
+>Visitor_54834 : Symbol(Visitor_54834, Decl(correlatedUnions.ts, 361, 2))
+
+) {
+  v[node.type](node);
+>v : Symbol(v, Decl(correlatedUnions.ts, 368, 35))
+>node.type : Symbol(type, Decl(correlatedUnions.ts, 360, 66), Decl(correlatedUnions.ts, 336, 16), Decl(correlatedUnions.ts, 360, 66), Decl(correlatedUnions.ts, 340, 16), Decl(correlatedUnions.ts, 360, 66) ... and 3 more)
+>node : Symbol(node, Decl(correlatedUnions.ts, 367, 56))
+>type : Symbol(type, Decl(correlatedUnions.ts, 360, 66), Decl(correlatedUnions.ts, 336, 16), Decl(correlatedUnions.ts, 360, 66), Decl(correlatedUnions.ts, 340, 16), Decl(correlatedUnions.ts, 360, 66) ... and 3 more)
+>node : Symbol(node, Decl(correlatedUnions.ts, 367, 56))
+}
+
diff --git a/tests/baselines/reference/correlatedUnions.types b/tests/baselines/reference/correlatedUnions.types
index 8d328d6c66f79..eae43b70f8c44 100644
--- a/tests/baselines/reference/correlatedUnions.types
+++ b/tests/baselines/reference/correlatedUnions.types
@@ -900,3 +900,202 @@ function getValueConcrete<K extends keyof Foo1>(
 >k : K
 }
 
+// repro from https://github.com/microsoft/TypeScript/issues/54680
+
+type A_54680 = {
+>A_54680 : { type: "A"; value: string; }
+
+  type: "A";
+>type : "A"
+
+  value: string;
+>value : string
+
+};
+
+type B_54680 = {
+>B_54680 : { type: "B"; value: number; }
+
+  type: "B";
+>type : "B"
+
+  value: number;
+>value : number
+
+};
+
+type Message_54680 = A_54680 | B_54680;
+>Message_54680 : A_54680 | B_54680
+
+function handle_54680_1<M extends Message_54680>(callbacks: {
+>handle_54680_1 : <M extends Message_54680>(callbacks: { [K in M["type"]]: (msg: Extract<M, { type: K; }>["value"]) => unknown; }) => void
+>callbacks : { [K in M["type"]]: (msg: Extract<M, { type: K; }>["value"]) => unknown; }
+
+  [K in M["type"]]: (msg: Extract<M, { type: K }>["value"]) => unknown;
+>msg : Extract<M, { type: K; }>["value"]
+>type : K
+
+}) {
+  window.addEventListener("message", (event) => {
+>window.addEventListener("message", (event) => {    const msg = event.data as M;    callbacks[msg.type as keyof typeof callbacks](msg.value);  }) : void
+>window.addEventListener : { <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; } & { <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; }
+>window : Window & typeof globalThis
+>addEventListener : { <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; } & { <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; }
+>"message" : "message"
+>(event) => {    const msg = event.data as M;    callbacks[msg.type as keyof typeof callbacks](msg.value);  } : (this: Window, event: MessageEvent<any>) => void
+>event : MessageEvent<any>
+
+    const msg = event.data as M;
+>msg : M
+>event.data as M : M
+>event.data : any
+>event : MessageEvent<any>
+>data : any
+
+    callbacks[msg.type as keyof typeof callbacks](msg.value);
+>callbacks[msg.type as keyof typeof callbacks](msg.value) : unknown
+>callbacks[msg.type as keyof typeof callbacks] : { [K in M["type"]]: (msg: Extract<M, { type: K; }>["value"]) => unknown; }[M["type"]]
+>callbacks : { [K in M["type"]]: (msg: Extract<M, { type: K; }>["value"]) => unknown; }
+>msg.type as keyof typeof callbacks : M["type"]
+>msg.type : "A" | "B"
+>msg : Message_54680
+>type : "A" | "B"
+>callbacks : { [K in M["type"]]: (msg: Extract<M, { type: K; }>["value"]) => unknown; }
+>msg.value : string | number
+>msg : Message_54680
+>value : string | number
+
+  });
+}
+
+function handle_54680_2<M extends Message_54680>(callbacks: {
+>handle_54680_2 : <M extends Message_54680>(callbacks: { [K in M["type"]]: (msg: (M & { type: K; })["value"]) => unknown; }) => void
+>callbacks : { [K in M["type"]]: (msg: (M & { type: K; })["value"]) => unknown; }
+
+  [K in M["type"]]: (msg: (M & { type: K })["value"]) => unknown;
+>msg : (M & { type: K; })["value"]
+>type : K
+
+}) {
+  window.addEventListener("message", (event) => {
+>window.addEventListener("message", (event) => {    const msg = event.data as M;    callbacks[msg.type as keyof typeof callbacks](msg.value);  }) : void
+>window.addEventListener : { <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; } & { <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; }
+>window : Window & typeof globalThis
+>addEventListener : { <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; } & { <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; }
+>"message" : "message"
+>(event) => {    const msg = event.data as M;    callbacks[msg.type as keyof typeof callbacks](msg.value);  } : (this: Window, event: MessageEvent<any>) => void
+>event : MessageEvent<any>
+
+    const msg = event.data as M;
+>msg : M
+>event.data as M : M
+>event.data : any
+>event : MessageEvent<any>
+>data : any
+
+    callbacks[msg.type as keyof typeof callbacks](msg.value);
+>callbacks[msg.type as keyof typeof callbacks](msg.value) : unknown
+>callbacks[msg.type as keyof typeof callbacks] : { [K in M["type"]]: (msg: (M & { type: K; })["value"]) => unknown; }[M["type"]]
+>callbacks : { [K in M["type"]]: (msg: (M & { type: K; })["value"]) => unknown; }
+>msg.type as keyof typeof callbacks : M["type"]
+>msg.type : "A" | "B"
+>msg : Message_54680
+>type : "A" | "B"
+>callbacks : { [K in M["type"]]: (msg: (M & { type: K; })["value"]) => unknown; }
+>msg.value : string | number
+>msg : Message_54680
+>value : string | number
+
+  });
+}
+
+// repro from https://github.com/microsoft/TypeScript/issues/54834
+
+type NumericLiteral_54834 = {
+>NumericLiteral_54834 : { value: number; type: "NumericLiteral"; }
+
+  value: number;
+>value : number
+
+  type: "NumericLiteral";
+>type : "NumericLiteral"
+
+};
+type StringLiteral_54834 = {
+>StringLiteral_54834 : { value: string; type: "StringLiteral"; }
+
+  value: string;
+>value : string
+
+  type: "StringLiteral";
+>type : "StringLiteral"
+
+};
+type Identifier_54834 = {
+>Identifier_54834 : { name: string; type: "Identifier"; }
+
+  name: string;
+>name : string
+
+  type: "Identifier";
+>type : "Identifier"
+
+};
+type CallExpression_54834 = {
+>CallExpression_54834 : { name: string; arguments: DropbearNode_54834[]; type: "CallExpression"; }
+
+  name: string;
+>name : string
+
+  arguments: DropbearNode_54834[];
+>arguments : DropbearNode_54834[]
+
+  type: "CallExpression";
+>type : "CallExpression"
+
+};
+
+type DropbearNode_54834 =
+>DropbearNode_54834 : NumericLiteral_54834 | StringLiteral_54834 | Identifier_54834 | CallExpression_54834
+
+  | NumericLiteral_54834
+  | StringLiteral_54834
+  | Identifier_54834
+  | CallExpression_54834;
+
+type TypeMap_54834 = {
+>TypeMap_54834 : { NumericLiteral: NumericLiteral_54834; StringLiteral: StringLiteral_54834; Identifier: Identifier_54834; CallExpression: CallExpression_54834; }
+
+  [K in DropbearNode_54834["type"]]: Extract<DropbearNode_54834, { type: K }>;
+>type : K
+
+};
+
+type Visitor_54834 = {
+>Visitor_54834 : { NumericLiteral: (node: Readonly<NumericLiteral_54834>) => void; StringLiteral: (node: Readonly<StringLiteral_54834>) => void; Identifier: (node: Readonly<Identifier_54834>) => void; CallExpression: (node: Readonly<CallExpression_54834>) => void; }
+
+  [K in keyof TypeMap_54834]: (node: Readonly<TypeMap_54834[K]>) => void;
+>node : Readonly<TypeMap_54834[K]>
+
+};
+
+function visitNode_54834<K extends keyof TypeMap_54834>(
+>visitNode_54834 : <K extends "NumericLiteral" | "StringLiteral" | "Identifier" | "CallExpression">(node: Readonly<TypeMap_54834[K]>, v: Visitor_54834) => void
+
+  node: Readonly<TypeMap_54834[K]>,
+>node : Readonly<TypeMap_54834[K]>
+
+  v: Visitor_54834
+>v : Visitor_54834
+
+) {
+  v[node.type](node);
+>v[node.type](node) : void
+>v[node.type] : Visitor_54834[TypeMap_54834[K]["type"]]
+>v : Visitor_54834
+>node.type : TypeMap_54834[K]["type"]
+>node : Readonly<TypeMap_54834[K]>
+>type : TypeMap_54834[K]["type"]
+>node : Readonly<TypeMap_54834[K]>
+}
+
diff --git a/tests/cases/compiler/correlatedUnions.ts b/tests/cases/compiler/correlatedUnions.ts
index 460ddf408a104..91c50b9ddf02f 100644
--- a/tests/cases/compiler/correlatedUnions.ts
+++ b/tests/cases/compiler/correlatedUnions.ts
@@ -301,3 +301,76 @@ function getValueConcrete<K extends keyof Foo1>(
 ): Foo1[K] | undefined {
   return o[k];
 }
+
+// repro from https://github.com/microsoft/TypeScript/issues/54680
+
+type A_54680 = {
+  type: "A";
+  value: string;
+};
+
+type B_54680 = {
+  type: "B";
+  value: number;
+};
+
+type Message_54680 = A_54680 | B_54680;
+
+function handle_54680_1<M extends Message_54680>(callbacks: {
+  [K in M["type"]]: (msg: Extract<M, { type: K }>["value"]) => unknown;
+}) {
+  window.addEventListener("message", (event) => {
+    const msg = event.data as M;
+    callbacks[msg.type as keyof typeof callbacks](msg.value);
+  });
+}
+
+function handle_54680_2<M extends Message_54680>(callbacks: {
+  [K in M["type"]]: (msg: (M & { type: K })["value"]) => unknown;
+}) {
+  window.addEventListener("message", (event) => {
+    const msg = event.data as M;
+    callbacks[msg.type as keyof typeof callbacks](msg.value);
+  });
+}
+
+// repro from https://github.com/microsoft/TypeScript/issues/54834
+
+type NumericLiteral_54834 = {
+  value: number;
+  type: "NumericLiteral";
+};
+type StringLiteral_54834 = {
+  value: string;
+  type: "StringLiteral";
+};
+type Identifier_54834 = {
+  name: string;
+  type: "Identifier";
+};
+type CallExpression_54834 = {
+  name: string;
+  arguments: DropbearNode_54834[];
+  type: "CallExpression";
+};
+
+type DropbearNode_54834 =
+  | NumericLiteral_54834
+  | StringLiteral_54834
+  | Identifier_54834
+  | CallExpression_54834;
+
+type TypeMap_54834 = {
+  [K in DropbearNode_54834["type"]]: Extract<DropbearNode_54834, { type: K }>;
+};
+
+type Visitor_54834 = {
+  [K in keyof TypeMap_54834]: (node: Readonly<TypeMap_54834[K]>) => void;
+};
+
+function visitNode_54834<K extends keyof TypeMap_54834>(
+  node: Readonly<TypeMap_54834[K]>,
+  v: Visitor_54834
+) {
+  v[node.type](node);
+}