diff --git a/src/observable/list/BaseMappedList.ts b/src/observable/list/BaseMappedList.ts
index f2203d34..b5a669d1 100644
--- a/src/observable/list/BaseMappedList.ts
+++ b/src/observable/list/BaseMappedList.ts
@@ -21,15 +21,15 @@ import {findAndUpdateInArray} from "./common";
 export type Mapper<F,T> = (value: F) => T
 export type Updater<F,T> = (mappedValue: T, params: any, value: F) => void;
 
-export class BaseMappedList<F,T> extends BaseObservableList<T> {
+export class BaseMappedList<F,T,R = T> extends BaseObservableList<T> {
     protected _sourceList: BaseObservableList<F>;
     protected _sourceUnsubscribe: (() => void) | null = null;
-    _mapper: Mapper<F,T>;
+    _mapper: Mapper<F,R>;
     _updater: Updater<F,T>;
     _removeCallback?: (value: T) => void;
     _mappedValues: T[] | null = null;
 
-    constructor(sourceList: BaseObservableList<F>, mapper: Mapper<F,T>, updater: Updater<F,T>, removeCallback?: (value: T) => void) {
+    constructor(sourceList: BaseObservableList<F>, mapper: Mapper<F,R>, updater: Updater<F,T>, removeCallback?: (value: T) => void) {
         super();
         this._sourceList = sourceList;
         this._mapper = mapper;
@@ -50,12 +50,12 @@ export class BaseMappedList<F,T> extends BaseObservableList<T> {
     }
 }
 
-export function runAdd<F,T>(list: BaseMappedList<F,T>, index: number, mappedValue: T): void {
+export function runAdd<F,T,R>(list: BaseMappedList<F,T,R>, index: number, mappedValue: T): void {
     list._mappedValues!.splice(index, 0, mappedValue);
     list.emitAdd(index, mappedValue);
 }
 
-export function runUpdate<F,T>(list: BaseMappedList<F,T>, index: number, value: F, params: any): void {
+export function runUpdate<F,T,R>(list: BaseMappedList<F,T,R>, index: number, value: F, params: any): void {
     const mappedValue = list._mappedValues![index];
     if (list._updater) {
         list._updater(mappedValue, params, value);
@@ -63,7 +63,7 @@ export function runUpdate<F,T>(list: BaseMappedList<F,T>, index: number, value:
     list.emitUpdate(index, mappedValue, params);
 }
 
-export function runRemove<F,T>(list: BaseMappedList<F,T>, index: number): void {
+export function runRemove<F,T,R>(list: BaseMappedList<F,T,R>, index: number): void {
     const mappedValue = list._mappedValues![index];
     list._mappedValues!.splice(index, 1);
     if (list._removeCallback) {
@@ -72,14 +72,14 @@ export function runRemove<F,T>(list: BaseMappedList<F,T>, index: number): void {
     list.emitRemove(index, mappedValue);
 }
 
-export function runMove<F,T>(list: BaseMappedList<F,T>, fromIdx: number, toIdx: number): void {
+export function runMove<F,T,R>(list: BaseMappedList<F,T,R>, fromIdx: number, toIdx: number): void {
     const mappedValue = list._mappedValues![fromIdx];
     list._mappedValues!.splice(fromIdx, 1);
     list._mappedValues!.splice(toIdx, 0, mappedValue);
     list.emitMove(fromIdx, toIdx, mappedValue);
 }
 
-export function runReset<F,T>(list: BaseMappedList<F,T>): void {
+export function runReset<F,T,R>(list: BaseMappedList<F,T,R>): void {
     list._mappedValues = [];
     list.emitReset();
 }