diff --git a/src/queue.js b/src/queue.js
index a261761..c2e6d44 100644
--- a/src/queue.js
+++ b/src/queue.js
@@ -15,10 +15,11 @@ function queue() {
     },
 
     flush() {
-      if (!completed) {
+      if (completed === null) {
         completed = new Promise(function (resolve) {
           window.setTimeout(function () {
             flush();
+            completed = null;
             resolve();
           }, 0);
         });
diff --git a/test/queue.test.js b/test/queue.test.js
index 5be28f2..3531b52 100644
--- a/test/queue.test.js
+++ b/test/queue.test.js
@@ -33,3 +33,18 @@ test('flush will run fns added after initial call', () => {
     expect(fn2.mock.calls.length).toEqual(1);
   });
 });
+
+test('flush will run again after delayed completion', (done) => {
+  let q = queue();
+  let fn = jest.fn();
+  let fn2 = jest.fn();
+  q.add(fn);
+
+  q.flush().then(() => {
+    q.add(fn2);
+    q.flush().then(() => {
+      expect(fn2.mock.calls.length).toEqual(1);
+      done();
+    });
+  });
+});