diff --git a/src/observable/list/BaseMappedList.js b/src/observable/list/BaseMappedList.js
index 19c98b88..314c083e 100644
--- a/src/observable/list/BaseMappedList.js
+++ b/src/observable/list/BaseMappedList.js
@@ -16,7 +16,7 @@ limitations under the License.
 */
 
 import {BaseObservableList} from "./BaseObservableList";
-import {findAndUpdateInArray} from "./common.js";
+import {findAndUpdateInArray} from "./common";
 
 export class BaseMappedList extends BaseObservableList {
     constructor(sourceList, mapper, updater, removeCallback) {
diff --git a/src/observable/list/SortedArray.js b/src/observable/list/SortedArray.js
index 29e0c3f1..874d1b04 100644
--- a/src/observable/list/SortedArray.js
+++ b/src/observable/list/SortedArray.js
@@ -16,7 +16,7 @@ limitations under the License.
 
 import {BaseObservableList} from "./BaseObservableList";
 import {sortedIndex} from "../../utils/sortedIndex.js";
-import {findAndUpdateInArray} from "./common.js";
+import {findAndUpdateInArray} from "./common";
 
 export class SortedArray extends BaseObservableList {
     constructor(comparator) {
diff --git a/src/observable/list/common.js b/src/observable/list/common.ts
similarity index 100%
rename from src/observable/list/common.js
rename to src/observable/list/common.ts