diff -r 09105051b9f4 Lib/idlelib/PyShell.py
--- a/Lib/idlelib/PyShell.py	Sun Nov 03 21:31:38 2013 +0200
+++ b/Lib/idlelib/PyShell.py	Mon Nov 04 10:44:36 2013 +0200
@@ -1334,8 +1334,10 @@
     def write(self, s):
         if self.closed:
             raise ValueError("write to closed file")
-        if not isinstance(s, str):
-            raise TypeError('must be str, not ' + type(s).__name__)
+        if type(s) is not str:
+            if not isinstance(s, str):
+                raise TypeError('must be str, not ' + type(s).__name__)
+            s = str(s)
         return self.shell.write(s, self.tags)