diff --git a/tests/baselines/reference/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.symbols b/tests/baselines/reference/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.symbols
new file mode 100644
index 0000000000000..a7f398bb7bb28
--- /dev/null
+++ b/tests/baselines/reference/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.symbols
@@ -0,0 +1,36 @@
+//// [tests/cases/compiler/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts] ////
+
+=== mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts ===
+// https://github.com/microsoft/TypeScript/pull/55774#issuecomment-1813484949
+
+type Mapper<T> = {
+>Mapper : Symbol(Mapper, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 0, 0))
+>T : Symbol(T, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 2, 12))
+
+  [K in keyof T as K]: T[K] extends NonNullable<T[K]> ? T[K] : never;
+>K : Symbol(K, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 3, 3))
+>T : Symbol(T, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 2, 12))
+>K : Symbol(K, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 3, 3))
+>T : Symbol(T, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 2, 12))
+>K : Symbol(K, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 3, 3))
+>NonNullable : Symbol(NonNullable, Decl(lib.es5.d.ts, --, --))
+>T : Symbol(T, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 2, 12))
+>K : Symbol(K, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 3, 3))
+>T : Symbol(T, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 2, 12))
+>K : Symbol(K, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 3, 3))
+
+};
+
+type Mapped = Mapper<[1, 2]>;
+>Mapped : Symbol(Mapped, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 4, 2))
+>Mapper : Symbol(Mapper, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 0, 0))
+
+type Keys = keyof Mapper<[1, 2]>;
+>Keys : Symbol(Keys, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 6, 29))
+>Mapper : Symbol(Mapper, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 0, 0))
+
+type SomeType = Mapped[Keys]; // ok
+>SomeType : Symbol(SomeType, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 7, 33))
+>Mapped : Symbol(Mapped, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 4, 2))
+>Keys : Symbol(Keys, Decl(mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts, 6, 29))
+
diff --git a/tests/baselines/reference/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.types b/tests/baselines/reference/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.types
new file mode 100644
index 0000000000000..314ee7c796ec8
--- /dev/null
+++ b/tests/baselines/reference/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.types
@@ -0,0 +1,20 @@
+//// [tests/cases/compiler/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts] ////
+
+=== mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts ===
+// https://github.com/microsoft/TypeScript/pull/55774#issuecomment-1813484949
+
+type Mapper<T> = {
+>Mapper : Mapper<T>
+
+  [K in keyof T as K]: T[K] extends NonNullable<T[K]> ? T[K] : never;
+};
+
+type Mapped = Mapper<[1, 2]>;
+>Mapped : Mapper<[1, 2]>
+
+type Keys = keyof Mapper<[1, 2]>;
+>Keys : "0" | "1"
+
+type SomeType = Mapped[Keys]; // ok
+>SomeType : 2 | 1
+
diff --git a/tests/cases/compiler/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts b/tests/cases/compiler/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts
new file mode 100644
index 0000000000000..e20c9fce401f3
--- /dev/null
+++ b/tests/cases/compiler/mappedTypeHomomorphicTupleInstantiationNameTypeKeys.ts
@@ -0,0 +1,13 @@
+// @strict: true
+// @noEmit: true
+
+// https://github.com/microsoft/TypeScript/pull/55774#issuecomment-1813484949
+
+type Mapper<T> = {
+  [K in keyof T as K]: T[K] extends NonNullable<T[K]> ? T[K] : never;
+};
+
+type Mapped = Mapper<[1, 2]>;
+type Keys = keyof Mapper<[1, 2]>;
+
+type SomeType = Mapped[Keys]; // ok