diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 8a5d99e8f69af..e6084a4169743 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -36511,7 +36511,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         if (signatureHasRestParameter(signature)) {
             const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]);
             if (!isTupleType(restType)) {
-                return restType;
+                return isTypeAny(restType) ? anyArrayType : restType;
             }
             if (restType.target.hasRestElement) {
                 return sliceTupleType(restType, restType.target.fixedLength);
diff --git a/tests/baselines/reference/homomorphicMappedTypesAppliedToParametersUsedAsRest1.symbols b/tests/baselines/reference/homomorphicMappedTypesAppliedToParametersUsedAsRest1.symbols
new file mode 100644
index 0000000000000..c21b8088b1f4e
--- /dev/null
+++ b/tests/baselines/reference/homomorphicMappedTypesAppliedToParametersUsedAsRest1.symbols
@@ -0,0 +1,54 @@
+//// [tests/cases/compiler/homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts] ////
+
+=== homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts ===
+// https://github.com/microsoft/TypeScript/issues/29919
+
+type FuncParams<T> = T extends (...args: infer P) => any ? P : never;
+>FuncParams : Symbol(FuncParams, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 0, 0))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 2, 16))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 2, 16))
+>args : Symbol(args, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 2, 32))
+>P : Symbol(P, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 2, 46))
+>P : Symbol(P, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 2, 46))
+
+type Stringify<T> = {
+>Stringify : Symbol(Stringify, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 2, 69))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 3, 15))
+
+  [K in keyof T]: string;
+>K : Symbol(K, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 4, 3))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 3, 15))
+
+};
+type Optional<T> = {
+>Optional : Symbol(Optional, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 5, 2))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 6, 14))
+
+  [K in keyof T]?: T[K];
+>K : Symbol(K, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 7, 3))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 6, 14))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 6, 14))
+>K : Symbol(K, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 7, 3))
+
+};
+
+function doOptionalStuff<T>(func: T, ...params: Optional<FuncParams<T>>) {}
+>doOptionalStuff : Symbol(doOptionalStuff, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 8, 2))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 10, 25))
+>func : Symbol(func, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 10, 28))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 10, 25))
+>params : Symbol(params, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 10, 36))
+>Optional : Symbol(Optional, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 5, 2))
+>FuncParams : Symbol(FuncParams, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 0, 0))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 10, 25))
+
+function doStringStuff<T>(func: T, ...params: Stringify<FuncParams<T>>) {}
+>doStringStuff : Symbol(doStringStuff, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 10, 75))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 12, 23))
+>func : Symbol(func, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 12, 26))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 12, 23))
+>params : Symbol(params, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 12, 34))
+>Stringify : Symbol(Stringify, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 2, 69))
+>FuncParams : Symbol(FuncParams, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 0, 0))
+>T : Symbol(T, Decl(homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts, 12, 23))
+
diff --git a/tests/baselines/reference/homomorphicMappedTypesAppliedToParametersUsedAsRest1.types b/tests/baselines/reference/homomorphicMappedTypesAppliedToParametersUsedAsRest1.types
new file mode 100644
index 0000000000000..6ba932fdbada1
--- /dev/null
+++ b/tests/baselines/reference/homomorphicMappedTypesAppliedToParametersUsedAsRest1.types
@@ -0,0 +1,30 @@
+//// [tests/cases/compiler/homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts] ////
+
+=== homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts ===
+// https://github.com/microsoft/TypeScript/issues/29919
+
+type FuncParams<T> = T extends (...args: infer P) => any ? P : never;
+>FuncParams : FuncParams<T>
+>args : P
+
+type Stringify<T> = {
+>Stringify : Stringify<T>
+
+  [K in keyof T]: string;
+};
+type Optional<T> = {
+>Optional : Optional<T>
+
+  [K in keyof T]?: T[K];
+};
+
+function doOptionalStuff<T>(func: T, ...params: Optional<FuncParams<T>>) {}
+>doOptionalStuff : <T>(func: T, ...params: Optional<FuncParams<T>>) => void
+>func : T
+>params : Optional<FuncParams<T>>
+
+function doStringStuff<T>(func: T, ...params: Stringify<FuncParams<T>>) {}
+>doStringStuff : <T>(func: T, ...params: Stringify<FuncParams<T>>) => void
+>func : T
+>params : Stringify<FuncParams<T>>
+
diff --git a/tests/baselines/reference/inferTypes1.types b/tests/baselines/reference/inferTypes1.types
index 3ce2bf2dd5011..a24fb4ad85811 100644
--- a/tests/baselines/reference/inferTypes1.types
+++ b/tests/baselines/reference/inferTypes1.types
@@ -98,7 +98,7 @@ type T18 = ReturnType<Function>;  // Error
 >T18 : any
 
 type T19<T extends any[]> = ReturnType<(x: string, ...args: T) => T[]>;  // T[]
->T19 : T[]
+>T19 : T19<T>
 >x : string
 >args : T
 
@@ -123,12 +123,12 @@ type U15 = InstanceType<typeof Abstract>;  // Abstract
 >Abstract : typeof Abstract
 
 type U16<T extends any[]> = InstanceType<new (x: string, ...args: T) => T[]>;  // T[]
->U16 : T[]
+>U16 : U16<T>
 >x : string
 >args : T
 
 type U17<T extends any[]> = InstanceType<abstract new (x: string, ...args: T) => T[]>;  // T[]
->U17 : T[]
+>U17 : U17<T>
 >x : string
 >args : T
 
@@ -490,6 +490,6 @@ const result = invoker('test', true)({ test: (a: boolean) => 123 })
 >123 : 123
 
 type Foo2<A extends any[]> = ReturnType<(...args: A) => string>;
->Foo2 : string
+>Foo2 : Foo2<A>
 >args : A
 
diff --git a/tests/cases/compiler/homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts b/tests/cases/compiler/homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts
new file mode 100644
index 0000000000000..8ddcbaf58d6e7
--- /dev/null
+++ b/tests/cases/compiler/homomorphicMappedTypesAppliedToParametersUsedAsRest1.ts
@@ -0,0 +1,16 @@
+// @strict: true
+// @noEmit: true
+
+// https://github.com/microsoft/TypeScript/issues/29919
+
+type FuncParams<T> = T extends (...args: infer P) => any ? P : never;
+type Stringify<T> = {
+  [K in keyof T]: string;
+};
+type Optional<T> = {
+  [K in keyof T]?: T[K];
+};
+
+function doOptionalStuff<T>(func: T, ...params: Optional<FuncParams<T>>) {}
+
+function doStringStuff<T>(func: T, ...params: Stringify<FuncParams<T>>) {}