diff --git a/idlelib/idle_test/test_outwin.py b/idlelib/idle_test/test_outwin.py
index d6e85ad6..81f4aad7 100644
--- a/idlelib/idle_test/test_outwin.py
+++ b/idlelib/idle_test/test_outwin.py
@@ -1,6 +1,7 @@
 "Test outwin, coverage 76%."
 
 from idlelib import outwin
+import sys
 import unittest
 from test.support import requires
 from tkinter import Tk, Text
@@ -18,6 +19,10 @@ def setUpClass(cls):
         root.withdraw()
         w = cls.window = outwin.OutputWindow(None, None, None, root)
         cls.text = w.text = Text(root)
+        if sys.platform == 'darwin':  # Issue 112938
+            cls.text.update = cls.text.update_idletasks
+            # Without this, test write, writelines, and goto... fail.
+            # The reasons and why macOS-specific are unclear.
 
     @classmethod
     def tearDownClass(cls):
diff --git a/idlelib/outwin.py b/idlelib/outwin.py
index 5ed3f35a..8baa6575 100644
--- a/idlelib/outwin.py
+++ b/idlelib/outwin.py
@@ -112,7 +112,7 @@ def write(self, s, tags=(), mark="insert"):
         assert isinstance(s, str)
         self.text.insert(mark, s, tags)
         self.text.see(mark)
-        self.text.update_idletasks()
+        self.text.update()
         return len(s)
 
     def writelines(self, lines):