diff --git a/tests/baselines/reference/keyofAndIndexedAccess.js b/tests/baselines/reference/keyofAndIndexedAccess.js
index 3ad7bdd79f8..f5c2624fc40 100644
--- a/tests/baselines/reference/keyofAndIndexedAccess.js
+++ b/tests/baselines/reference/keyofAndIndexedAccess.js
@@ -463,6 +463,33 @@ let MyThingy: { [key in KeyTypes]: string[] };
 function addToMyThingy<S extends KeyTypes>(key: S) {
     MyThingy[key].push("a");
 }
+
+// Repro from #13285
+
+function updateIds<T extends Record<K, string>, K extends string>(
+    obj: T,
+    idFields: K[],
+    idMapping: { [oldId: string]: string }
+): Record<K, string> {
+    for (const idField of idFields) {
+        const newId = idMapping[obj[idField]];
+        if (newId) {
+            obj[idField] = newId;
+        }
+    }
+    return obj;
+}
+
+// Repro from #13285
+
+function updateIds2<T extends { [x: string]: string }, K extends keyof T>(
+    obj: T,
+    key: K,
+    stringMap: { [oldId: string]: string }
+) {
+    var x = obj[key];
+    stringMap[x]; // Should be OK.
+}
 
 
 //// [keyofAndIndexedAccess.js]
@@ -769,6 +796,22 @@ var MyThingy;
 function addToMyThingy(key) {
     MyThingy[key].push("a");
 }
+// Repro from #13285
+function updateIds(obj, idFields, idMapping) {
+    for (var _i = 0, idFields_1 = idFields; _i < idFields_1.length; _i++) {
+        var idField = idFields_1[_i];
+        var newId = idMapping[obj[idField]];
+        if (newId) {
+            obj[idField] = newId;
+        }
+    }
+    return obj;
+}
+// Repro from #13285
+function updateIds2(obj, key, stringMap) {
+    var x = obj[key];
+    stringMap[x]; // Should be OK.
+}
 
 
 //// [keyofAndIndexedAccess.d.ts]
@@ -986,3 +1029,11 @@ declare let MyThingy: {
     [key in KeyTypes]: string[];
 };
 declare function addToMyThingy<S extends KeyTypes>(key: S): void;
+declare function updateIds<T extends Record<K, string>, K extends string>(obj: T, idFields: K[], idMapping: {
+    [oldId: string]: string;
+}): Record<K, string>;
+declare function updateIds2<T extends {
+    [x: string]: string;
+}, K extends keyof T>(obj: T, key: K, stringMap: {
+    [oldId: string]: string;
+}): void;
diff --git a/tests/baselines/reference/keyofAndIndexedAccess.symbols b/tests/baselines/reference/keyofAndIndexedAccess.symbols
index fb8129a5301..a6eb03dd6e5 100644
--- a/tests/baselines/reference/keyofAndIndexedAccess.symbols
+++ b/tests/baselines/reference/keyofAndIndexedAccess.symbols
@@ -1699,3 +1699,83 @@ function addToMyThingy<S extends KeyTypes>(key: S) {
 >push : Symbol(Array.push, Decl(lib.d.ts, --, --))
 }
 
+// Repro from #13285
+
+function updateIds<T extends Record<K, string>, K extends string>(
+>updateIds : Symbol(updateIds, Decl(keyofAndIndexedAccess.ts, 463, 1))
+>T : Symbol(T, Decl(keyofAndIndexedAccess.ts, 467, 19))
+>Record : Symbol(Record, Decl(lib.d.ts, --, --))
+>K : Symbol(K, Decl(keyofAndIndexedAccess.ts, 467, 47))
+>K : Symbol(K, Decl(keyofAndIndexedAccess.ts, 467, 47))
+
+    obj: T,
+>obj : Symbol(obj, Decl(keyofAndIndexedAccess.ts, 467, 66))
+>T : Symbol(T, Decl(keyofAndIndexedAccess.ts, 467, 19))
+
+    idFields: K[],
+>idFields : Symbol(idFields, Decl(keyofAndIndexedAccess.ts, 468, 11))
+>K : Symbol(K, Decl(keyofAndIndexedAccess.ts, 467, 47))
+
+    idMapping: { [oldId: string]: string }
+>idMapping : Symbol(idMapping, Decl(keyofAndIndexedAccess.ts, 469, 18))
+>oldId : Symbol(oldId, Decl(keyofAndIndexedAccess.ts, 470, 18))
+
+): Record<K, string> {
+>Record : Symbol(Record, Decl(lib.d.ts, --, --))
+>K : Symbol(K, Decl(keyofAndIndexedAccess.ts, 467, 47))
+
+    for (const idField of idFields) {
+>idField : Symbol(idField, Decl(keyofAndIndexedAccess.ts, 472, 14))
+>idFields : Symbol(idFields, Decl(keyofAndIndexedAccess.ts, 468, 11))
+
+        const newId = idMapping[obj[idField]];
+>newId : Symbol(newId, Decl(keyofAndIndexedAccess.ts, 473, 13))
+>idMapping : Symbol(idMapping, Decl(keyofAndIndexedAccess.ts, 469, 18))
+>obj : Symbol(obj, Decl(keyofAndIndexedAccess.ts, 467, 66))
+>idField : Symbol(idField, Decl(keyofAndIndexedAccess.ts, 472, 14))
+
+        if (newId) {
+>newId : Symbol(newId, Decl(keyofAndIndexedAccess.ts, 473, 13))
+
+            obj[idField] = newId;
+>obj : Symbol(obj, Decl(keyofAndIndexedAccess.ts, 467, 66))
+>idField : Symbol(idField, Decl(keyofAndIndexedAccess.ts, 472, 14))
+>newId : Symbol(newId, Decl(keyofAndIndexedAccess.ts, 473, 13))
+        }
+    }
+    return obj;
+>obj : Symbol(obj, Decl(keyofAndIndexedAccess.ts, 467, 66))
+}
+
+// Repro from #13285
+
+function updateIds2<T extends { [x: string]: string }, K extends keyof T>(
+>updateIds2 : Symbol(updateIds2, Decl(keyofAndIndexedAccess.ts, 479, 1))
+>T : Symbol(T, Decl(keyofAndIndexedAccess.ts, 483, 20))
+>x : Symbol(x, Decl(keyofAndIndexedAccess.ts, 483, 33))
+>K : Symbol(K, Decl(keyofAndIndexedAccess.ts, 483, 54))
+>T : Symbol(T, Decl(keyofAndIndexedAccess.ts, 483, 20))
+
+    obj: T,
+>obj : Symbol(obj, Decl(keyofAndIndexedAccess.ts, 483, 74))
+>T : Symbol(T, Decl(keyofAndIndexedAccess.ts, 483, 20))
+
+    key: K,
+>key : Symbol(key, Decl(keyofAndIndexedAccess.ts, 484, 11))
+>K : Symbol(K, Decl(keyofAndIndexedAccess.ts, 483, 54))
+
+    stringMap: { [oldId: string]: string }
+>stringMap : Symbol(stringMap, Decl(keyofAndIndexedAccess.ts, 485, 11))
+>oldId : Symbol(oldId, Decl(keyofAndIndexedAccess.ts, 486, 18))
+
+) {
+    var x = obj[key];
+>x : Symbol(x, Decl(keyofAndIndexedAccess.ts, 488, 7))
+>obj : Symbol(obj, Decl(keyofAndIndexedAccess.ts, 483, 74))
+>key : Symbol(key, Decl(keyofAndIndexedAccess.ts, 484, 11))
+
+    stringMap[x]; // Should be OK.
+>stringMap : Symbol(stringMap, Decl(keyofAndIndexedAccess.ts, 485, 11))
+>x : Symbol(x, Decl(keyofAndIndexedAccess.ts, 488, 7))
+}
+
diff --git a/tests/baselines/reference/keyofAndIndexedAccess.types b/tests/baselines/reference/keyofAndIndexedAccess.types
index ccf0bde4e1c..920758c8beb 100644
--- a/tests/baselines/reference/keyofAndIndexedAccess.types
+++ b/tests/baselines/reference/keyofAndIndexedAccess.types
@@ -2013,3 +2013,89 @@ function addToMyThingy<S extends KeyTypes>(key: S) {
 >"a" : "a"
 }
 
+// Repro from #13285
+
+function updateIds<T extends Record<K, string>, K extends string>(
+>updateIds : <T extends Record<K, string>, K extends string>(obj: T, idFields: K[], idMapping: { [oldId: string]: string; }) => Record<K, string>
+>T : T
+>Record : Record<K, T>
+>K : K
+>K : K
+
+    obj: T,
+>obj : T
+>T : T
+
+    idFields: K[],
+>idFields : K[]
+>K : K
+
+    idMapping: { [oldId: string]: string }
+>idMapping : { [oldId: string]: string; }
+>oldId : string
+
+): Record<K, string> {
+>Record : Record<K, T>
+>K : K
+
+    for (const idField of idFields) {
+>idField : K
+>idFields : K[]
+
+        const newId = idMapping[obj[idField]];
+>newId : { [oldId: string]: string; }[T[K]]
+>idMapping[obj[idField]] : { [oldId: string]: string; }[T[K]]
+>idMapping : { [oldId: string]: string; }
+>obj[idField] : T[K]
+>obj : T
+>idField : K
+
+        if (newId) {
+>newId : { [oldId: string]: string; }[T[K]]
+
+            obj[idField] = newId;
+>obj[idField] = newId : { [oldId: string]: string; }[T[K]]
+>obj[idField] : T[K]
+>obj : T
+>idField : K
+>newId : { [oldId: string]: string; }[T[K]]
+        }
+    }
+    return obj;
+>obj : T
+}
+
+// Repro from #13285
+
+function updateIds2<T extends { [x: string]: string }, K extends keyof T>(
+>updateIds2 : <T extends { [x: string]: string; }, K extends keyof T>(obj: T, key: K, stringMap: { [oldId: string]: string; }) => void
+>T : T
+>x : string
+>K : K
+>T : T
+
+    obj: T,
+>obj : T
+>T : T
+
+    key: K,
+>key : K
+>K : K
+
+    stringMap: { [oldId: string]: string }
+>stringMap : { [oldId: string]: string; }
+>oldId : string
+
+) {
+    var x = obj[key];
+>x : T[K]
+>obj[key] : T[K]
+>obj : T
+>key : K
+
+    stringMap[x]; // Should be OK.
+>stringMap[x] : { [oldId: string]: string; }[T[K]]
+>stringMap : { [oldId: string]: string; }
+>x : T[K]
+}
+
diff --git a/tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts b/tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts
index 0ef73c736f4..770dc2ead98 100644
--- a/tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts
+++ b/tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts
@@ -464,3 +464,30 @@ let MyThingy: { [key in KeyTypes]: string[] };
 function addToMyThingy<S extends KeyTypes>(key: S) {
     MyThingy[key].push("a");
 }
+
+// Repro from #13285
+
+function updateIds<T extends Record<K, string>, K extends string>(
+    obj: T,
+    idFields: K[],
+    idMapping: { [oldId: string]: string }
+): Record<K, string> {
+    for (const idField of idFields) {
+        const newId = idMapping[obj[idField]];
+        if (newId) {
+            obj[idField] = newId;
+        }
+    }
+    return obj;
+}
+
+// Repro from #13285
+
+function updateIds2<T extends { [x: string]: string }, K extends keyof T>(
+    obj: T,
+    key: K,
+    stringMap: { [oldId: string]: string }
+) {
+    var x = obj[key];
+    stringMap[x]; // Should be OK.
+}