diff --git a/ansible_mitogen/runner.py b/ansible_mitogen/runner.py
index 04c70e78..30c36be7 100644
--- a/ansible_mitogen/runner.py
+++ b/ansible_mitogen/runner.py
@@ -40,6 +40,7 @@ import atexit
 import codecs
 import imp
 import os
+import re
 import shlex
 import shutil
 import sys
@@ -806,11 +807,20 @@ class NewStyleRunner(ScriptRunner):
     def _setup_args(self):
         pass
 
+    # issue #555: in old times it was considered good form to reload sys and
+    # change the default encoding. This hack was removed from Ansible long ago,
+    # but not before permeating into many third party modules.
+    PREHISTORIC_HACK_RE = re.compile(
+        b(r'reload\s*\(\s*sys\s*\)\s*'
+          r'sys\s*\.\s*setdefaultencoding\([^)]+\)')
+    )
+
     def _setup_program(self):
-        self.source = ansible_mitogen.target.get_small_file(
+        source = ansible_mitogen.target.get_small_file(
             context=self.service_context,
             path=self.path,
         )
+        self.source = self.PREHISTORIC_HACK_RE.sub(b(''), source)
 
     def _get_code(self):
         try:
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 165f8a45..11d3150f 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -45,6 +45,9 @@ Fixes
   action plug-ins that invoked :func:`_make_tmp_path` repeatedly could trigger
   an assertion failure.
 
+* `#555 <https://github.com/dw/mitogen/issues/555>`_: work around an old idiom
+  that reloaded :mod:`sys` in order to change the interpreter's default encoding.
+
 * `ffae0355 <https://github.com/dw/mitogen/commit/ffae0355>`_: needless
   information was removed from the documentation and installation procedure.
 
@@ -78,6 +81,7 @@ Thanks!
 Mitogen would not be possible without the support of users. A huge thanks for
 bug reports, testing, features and fixes in this release contributed by
 `Fabian Arrotin <https://github.com/arrfab>`_,
+`Giles Westwood <https://github.com/gilesw>`_,
 `Matt Layman <https://github.com/mblayman>`_,
 `Percy Grunwald <https://github.com/percygrunwald>`_,
 `Petr Enkov <https://github.com/enkov>`_,
diff --git a/tests/ansible/integration/runner/all.yml b/tests/ansible/integration/runner/all.yml
index dc23901f..19586547 100644
--- a/tests/ansible/integration/runner/all.yml
+++ b/tests/ansible/integration/runner/all.yml
@@ -12,6 +12,7 @@
 - include: custom_python_json_args_module.yml
 - include: custom_python_new_style_missing_interpreter.yml
 - include: custom_python_new_style_module.yml
+- include: custom_python_prehistoric_module.yml
 - include: custom_python_want_json_module.yml
 - include: custom_script_interpreter.yml
 - include: environment_isolation.yml
diff --git a/tests/ansible/integration/runner/custom_python_prehistoric_module.yml b/tests/ansible/integration/runner/custom_python_prehistoric_module.yml
new file mode 100644
index 00000000..458f3d2b
--- /dev/null
+++ b/tests/ansible/integration/runner/custom_python_prehistoric_module.yml
@@ -0,0 +1,10 @@
+# issue #555
+
+- name: integration/runner/custom_python_prehistoric_module.yml
+  hosts: test-targets
+  any_errors_fatal: true
+  tasks:
+    - custom_python_prehistoric_module:
+      register: out
+
+    - assert: that=out.ok
diff --git a/tests/ansible/lib/modules/custom_python_prehistoric_module.py b/tests/ansible/lib/modules/custom_python_prehistoric_module.py
new file mode 100644
index 00000000..d44f51ec
--- /dev/null
+++ b/tests/ansible/lib/modules/custom_python_prehistoric_module.py
@@ -0,0 +1,23 @@
+#!/usr/bin/python
+# issue #555: I'm a module that cutpastes an old hack.
+
+from ansible.module_utils.basic import AnsibleModule
+from ansible.module_utils.basic import get_module_path
+from ansible.module_utils import six
+
+import os
+import pwd
+import socket
+import sys
+
+import sys
+reload(sys)
+sys.setdefaultencoding('utf8')
+
+
+def main():
+    module = AnsibleModule(argument_spec={})
+    module.exit_json(ok=True)
+
+if __name__ == '__main__':
+    main()