diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 50cf05bad962d..2312d497c7c79 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -17624,7 +17624,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
 
     function getActualTypeVariable(type: Type): Type {
         if (type.flags & TypeFlags.Substitution) {
-            return (type as SubstitutionType).baseType;
+            return getActualTypeVariable((type as SubstitutionType).baseType);
         }
         if (type.flags & TypeFlags.IndexedAccess && (
             (type as IndexedAccessType).objectType.flags & TypeFlags.Substitution ||
diff --git a/tests/baselines/reference/inferRestArgumentsMappedTuple.js b/tests/baselines/reference/inferRestArgumentsMappedTuple.js
new file mode 100644
index 0000000000000..dec3b93df8ef7
--- /dev/null
+++ b/tests/baselines/reference/inferRestArgumentsMappedTuple.js
@@ -0,0 +1,30 @@
+//// [inferRestArgumentsMappedTuple.ts]
+type MyMappedType<Primitive extends any> = {
+	primitive: Primitive;
+};
+
+type TupleMapperOld<Tuple extends any[]> = {
+	[Key in keyof Tuple]: Tuple[Key] extends Tuple[number] ? MyMappedType<Tuple[Key]> : never;
+};
+
+type MyMappedTupleOld = TupleMapperOld<[string, number]>; // [MyMappedType<string>, MyMappedType<number>]
+
+declare function extractPrimitivesOld<Tuple extends any[]>(...mappedTypes: TupleMapperOld<Tuple>): Tuple;
+
+const myPrimitiveTupleOld: [string, number] = extractPrimitivesOld({ primitive: "" }, { primitive: 0 });
+
+type TupleMapperNew<Tuple extends any[]> = {
+	[Key in keyof Tuple]: MyMappedType<Tuple[Key]>;
+};
+
+type MyMappedTupleNew = TupleMapperNew<[string, number]>;
+
+declare function extractPrimitivesNew<Tuple extends any[]>(...mappedTypes: TupleMapperNew<Tuple>): Tuple;
+
+const myPrimitiveTupleNew: [string, number] = extractPrimitivesNew({ primitive: "" }, { primitive: 0 });
+
+
+//// [inferRestArgumentsMappedTuple.js]
+"use strict";
+var myPrimitiveTupleOld = extractPrimitivesOld({ primitive: "" }, { primitive: 0 });
+var myPrimitiveTupleNew = extractPrimitivesNew({ primitive: "" }, { primitive: 0 });
diff --git a/tests/baselines/reference/inferRestArgumentsMappedTuple.symbols b/tests/baselines/reference/inferRestArgumentsMappedTuple.symbols
new file mode 100644
index 0000000000000..7a763a93e3f7f
--- /dev/null
+++ b/tests/baselines/reference/inferRestArgumentsMappedTuple.symbols
@@ -0,0 +1,76 @@
+=== tests/cases/compiler/inferRestArgumentsMappedTuple.ts ===
+type MyMappedType<Primitive extends any> = {
+>MyMappedType : Symbol(MyMappedType, Decl(inferRestArgumentsMappedTuple.ts, 0, 0))
+>Primitive : Symbol(Primitive, Decl(inferRestArgumentsMappedTuple.ts, 0, 18))
+
+	primitive: Primitive;
+>primitive : Symbol(primitive, Decl(inferRestArgumentsMappedTuple.ts, 0, 44))
+>Primitive : Symbol(Primitive, Decl(inferRestArgumentsMappedTuple.ts, 0, 18))
+
+};
+
+type TupleMapperOld<Tuple extends any[]> = {
+>TupleMapperOld : Symbol(TupleMapperOld, Decl(inferRestArgumentsMappedTuple.ts, 2, 2))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 4, 20))
+
+	[Key in keyof Tuple]: Tuple[Key] extends Tuple[number] ? MyMappedType<Tuple[Key]> : never;
+>Key : Symbol(Key, Decl(inferRestArgumentsMappedTuple.ts, 5, 2))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 4, 20))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 4, 20))
+>Key : Symbol(Key, Decl(inferRestArgumentsMappedTuple.ts, 5, 2))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 4, 20))
+>MyMappedType : Symbol(MyMappedType, Decl(inferRestArgumentsMappedTuple.ts, 0, 0))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 4, 20))
+>Key : Symbol(Key, Decl(inferRestArgumentsMappedTuple.ts, 5, 2))
+
+};
+
+type MyMappedTupleOld = TupleMapperOld<[string, number]>; // [MyMappedType<string>, MyMappedType<number>]
+>MyMappedTupleOld : Symbol(MyMappedTupleOld, Decl(inferRestArgumentsMappedTuple.ts, 6, 2))
+>TupleMapperOld : Symbol(TupleMapperOld, Decl(inferRestArgumentsMappedTuple.ts, 2, 2))
+
+declare function extractPrimitivesOld<Tuple extends any[]>(...mappedTypes: TupleMapperOld<Tuple>): Tuple;
+>extractPrimitivesOld : Symbol(extractPrimitivesOld, Decl(inferRestArgumentsMappedTuple.ts, 8, 57))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 10, 38))
+>mappedTypes : Symbol(mappedTypes, Decl(inferRestArgumentsMappedTuple.ts, 10, 59))
+>TupleMapperOld : Symbol(TupleMapperOld, Decl(inferRestArgumentsMappedTuple.ts, 2, 2))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 10, 38))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 10, 38))
+
+const myPrimitiveTupleOld: [string, number] = extractPrimitivesOld({ primitive: "" }, { primitive: 0 });
+>myPrimitiveTupleOld : Symbol(myPrimitiveTupleOld, Decl(inferRestArgumentsMappedTuple.ts, 12, 5))
+>extractPrimitivesOld : Symbol(extractPrimitivesOld, Decl(inferRestArgumentsMappedTuple.ts, 8, 57))
+>primitive : Symbol(primitive, Decl(inferRestArgumentsMappedTuple.ts, 12, 68))
+>primitive : Symbol(primitive, Decl(inferRestArgumentsMappedTuple.ts, 12, 87))
+
+type TupleMapperNew<Tuple extends any[]> = {
+>TupleMapperNew : Symbol(TupleMapperNew, Decl(inferRestArgumentsMappedTuple.ts, 12, 104))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 14, 20))
+
+	[Key in keyof Tuple]: MyMappedType<Tuple[Key]>;
+>Key : Symbol(Key, Decl(inferRestArgumentsMappedTuple.ts, 15, 2))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 14, 20))
+>MyMappedType : Symbol(MyMappedType, Decl(inferRestArgumentsMappedTuple.ts, 0, 0))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 14, 20))
+>Key : Symbol(Key, Decl(inferRestArgumentsMappedTuple.ts, 15, 2))
+
+};
+
+type MyMappedTupleNew = TupleMapperNew<[string, number]>;
+>MyMappedTupleNew : Symbol(MyMappedTupleNew, Decl(inferRestArgumentsMappedTuple.ts, 16, 2))
+>TupleMapperNew : Symbol(TupleMapperNew, Decl(inferRestArgumentsMappedTuple.ts, 12, 104))
+
+declare function extractPrimitivesNew<Tuple extends any[]>(...mappedTypes: TupleMapperNew<Tuple>): Tuple;
+>extractPrimitivesNew : Symbol(extractPrimitivesNew, Decl(inferRestArgumentsMappedTuple.ts, 18, 57))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 20, 38))
+>mappedTypes : Symbol(mappedTypes, Decl(inferRestArgumentsMappedTuple.ts, 20, 59))
+>TupleMapperNew : Symbol(TupleMapperNew, Decl(inferRestArgumentsMappedTuple.ts, 12, 104))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 20, 38))
+>Tuple : Symbol(Tuple, Decl(inferRestArgumentsMappedTuple.ts, 20, 38))
+
+const myPrimitiveTupleNew: [string, number] = extractPrimitivesNew({ primitive: "" }, { primitive: 0 });
+>myPrimitiveTupleNew : Symbol(myPrimitiveTupleNew, Decl(inferRestArgumentsMappedTuple.ts, 22, 5))
+>extractPrimitivesNew : Symbol(extractPrimitivesNew, Decl(inferRestArgumentsMappedTuple.ts, 18, 57))
+>primitive : Symbol(primitive, Decl(inferRestArgumentsMappedTuple.ts, 22, 68))
+>primitive : Symbol(primitive, Decl(inferRestArgumentsMappedTuple.ts, 22, 87))
+
diff --git a/tests/baselines/reference/inferRestArgumentsMappedTuple.types b/tests/baselines/reference/inferRestArgumentsMappedTuple.types
new file mode 100644
index 0000000000000..eb8356ad91e17
--- /dev/null
+++ b/tests/baselines/reference/inferRestArgumentsMappedTuple.types
@@ -0,0 +1,57 @@
+=== tests/cases/compiler/inferRestArgumentsMappedTuple.ts ===
+type MyMappedType<Primitive extends any> = {
+>MyMappedType : MyMappedType<Primitive>
+
+	primitive: Primitive;
+>primitive : Primitive
+
+};
+
+type TupleMapperOld<Tuple extends any[]> = {
+>TupleMapperOld : TupleMapperOld<Tuple>
+
+	[Key in keyof Tuple]: Tuple[Key] extends Tuple[number] ? MyMappedType<Tuple[Key]> : never;
+};
+
+type MyMappedTupleOld = TupleMapperOld<[string, number]>; // [MyMappedType<string>, MyMappedType<number>]
+>MyMappedTupleOld : [MyMappedType<string>, MyMappedType<number>]
+
+declare function extractPrimitivesOld<Tuple extends any[]>(...mappedTypes: TupleMapperOld<Tuple>): Tuple;
+>extractPrimitivesOld : <Tuple extends any[]>(...mappedTypes: TupleMapperOld<Tuple>) => Tuple
+>mappedTypes : TupleMapperOld<Tuple>
+
+const myPrimitiveTupleOld: [string, number] = extractPrimitivesOld({ primitive: "" }, { primitive: 0 });
+>myPrimitiveTupleOld : [string, number]
+>extractPrimitivesOld({ primitive: "" }, { primitive: 0 }) : [string, number]
+>extractPrimitivesOld : <Tuple extends any[]>(...mappedTypes: TupleMapperOld<Tuple>) => Tuple
+>{ primitive: "" } : { primitive: string; }
+>primitive : string
+>"" : ""
+>{ primitive: 0 } : { primitive: number; }
+>primitive : number
+>0 : 0
+
+type TupleMapperNew<Tuple extends any[]> = {
+>TupleMapperNew : TupleMapperNew<Tuple>
+
+	[Key in keyof Tuple]: MyMappedType<Tuple[Key]>;
+};
+
+type MyMappedTupleNew = TupleMapperNew<[string, number]>;
+>MyMappedTupleNew : [MyMappedType<string>, MyMappedType<number>]
+
+declare function extractPrimitivesNew<Tuple extends any[]>(...mappedTypes: TupleMapperNew<Tuple>): Tuple;
+>extractPrimitivesNew : <Tuple extends any[]>(...mappedTypes: TupleMapperNew<Tuple>) => Tuple
+>mappedTypes : TupleMapperNew<Tuple>
+
+const myPrimitiveTupleNew: [string, number] = extractPrimitivesNew({ primitive: "" }, { primitive: 0 });
+>myPrimitiveTupleNew : [string, number]
+>extractPrimitivesNew({ primitive: "" }, { primitive: 0 }) : [string, number]
+>extractPrimitivesNew : <Tuple extends any[]>(...mappedTypes: TupleMapperNew<Tuple>) => Tuple
+>{ primitive: "" } : { primitive: string; }
+>primitive : string
+>"" : ""
+>{ primitive: 0 } : { primitive: number; }
+>primitive : number
+>0 : 0
+
diff --git a/tests/cases/compiler/inferRestArgumentsMappedTuple.ts b/tests/cases/compiler/inferRestArgumentsMappedTuple.ts
new file mode 100644
index 0000000000000..472f54b32428a
--- /dev/null
+++ b/tests/cases/compiler/inferRestArgumentsMappedTuple.ts
@@ -0,0 +1,25 @@
+// @strict: true
+
+type MyMappedType<Primitive extends any> = {
+	primitive: Primitive;
+};
+
+type TupleMapperOld<Tuple extends any[]> = {
+	[Key in keyof Tuple]: Tuple[Key] extends Tuple[number] ? MyMappedType<Tuple[Key]> : never;
+};
+
+type MyMappedTupleOld = TupleMapperOld<[string, number]>; // [MyMappedType<string>, MyMappedType<number>]
+
+declare function extractPrimitivesOld<Tuple extends any[]>(...mappedTypes: TupleMapperOld<Tuple>): Tuple;
+
+const myPrimitiveTupleOld: [string, number] = extractPrimitivesOld({ primitive: "" }, { primitive: 0 });
+
+type TupleMapperNew<Tuple extends any[]> = {
+	[Key in keyof Tuple]: MyMappedType<Tuple[Key]>;
+};
+
+type MyMappedTupleNew = TupleMapperNew<[string, number]>;
+
+declare function extractPrimitivesNew<Tuple extends any[]>(...mappedTypes: TupleMapperNew<Tuple>): Tuple;
+
+const myPrimitiveTupleNew: [string, number] = extractPrimitivesNew({ primitive: "" }, { primitive: 0 });