diff --git a/src/observable/map/ObservableMap.ts b/src/observable/map/ObservableMap.ts
index 719ce4b7..8ada1843 100644
--- a/src/observable/map/ObservableMap.ts
+++ b/src/observable/map/ObservableMap.ts
@@ -19,7 +19,7 @@ import {BaseObservableMap} from "./BaseObservableMap";
 export class ObservableMap<K, V> extends BaseObservableMap<K, V> {
     private readonly _values: Map<K, V>;
 
-    constructor(initialValues?: Iterable<[K, V]>) {
+    constructor(initialValues?: Iterable<readonly [K, V]>) {
         super();
         this._values = new Map(initialValues);
     }