1 files changed, 2 insertions, 2 deletions
diff --git a/packages/idb-bridge/src/tree/b+tree.ts b/packages/idb-bridge/src/tree/b+tree.ts
index 01187cdc2..783c6b049 100644
--- a/packages/idb-bridge/src/tree/b+tree.ts
+++ b/packages/idb-bridge/src/tree/b+tree.ts
@@ -823,7 +823,7 @@ if (Symbol && Symbol.iterator) // iterator is equivalent to entries()
 (BTree as any).prototype.setRange = BTree.prototype.setPairs;
 (BTree as any).prototype.add = BTree.prototype.set;
 
-function iterator<T>(next: () => {done:boolean,value?:T} = (() => ({ done:true, value:undefined }))): IterableIterator<T> {
+function iterator<T>(next: () => {done?:boolean,value?:T} = (() => ({ done:true, value:undefined }))): IterableIterator<T> {
   var result: any = { next };
   if (Symbol && Symbol.iterator)
     result[Symbol.iterator] = function() { return this; };
@@ -1348,4 +1348,4 @@ function check(fact: boolean, ...args: any[]) {
 }
 
 /** A BTree frozen in the empty state. */
-export const EmptyBTree = (() => { let t = new BTree(); t.freeze(); return t; })();
-\ No newline at end of file
+export const EmptyBTree = (() => { let t = new BTree(); t.freeze(); return t; })();