diff --git a/src/patch_promise.js b/src/patch_promise.js
index 1c2c49b..6b66635 100644
--- a/src/patch_promise.js
+++ b/src/patch_promise.js
@@ -5,9 +5,9 @@ export const patch_promise = window => {
     return
   }
 
-  const _then = Promise.prototype.then
+  const _then = window.Promise.prototype.then
 
-  Promise.prototype.then = function then(on_resolve, on_reject) {
+  window.Promise.prototype.then = function then(on_resolve, on_reject) {
     let children = window.get_children()
     if(children == null) {
       children = []
diff --git a/test/self_hosted_test.js b/test/self_hosted_test.js
index 30b4a42..3593c03 100644
--- a/test/self_hosted_test.js
+++ b/test/self_hosted_test.js
@@ -8,6 +8,7 @@ import * as pathlib from 'path'
 import {COMMANDS} from '../src/cmd.js'
 import {root_calltree_node} from '../src/calltree.js'
 import { assert_equal, test_initial_state, } from './utils.js'
+import {tests} from './test.js'
 
 // Should work same as src/filesystem.js:load_dir
 const load_dir = path => {
@@ -85,6 +86,6 @@ const run = root.children[0]
 assert_equal(root_calltree_node(state).ok, true)
 
 // Assert that run children are tests
-assert_equal(run.children.length > 100, true)
+assert_equal(run.children.length, tests.length)
 
 console.timeEnd('run')
diff --git a/test/utils.js b/test/utils.js
index 69fcd2c..24db328 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -154,7 +154,7 @@ export const test_only = (message, t) => test(message, t, true)
 export const run = Object.defineProperty(new Function('tests', `
     // Runs test, return failure or null if not failed
     const run_test = t => {
-      return Promise.resolve(t.test())
+      return Promise.resolve().then(t.test)
         .then(() => null)
         .catch(e => {
           if(globalThis.process != null) {