diff --git a/docs/changelog.rst b/docs/changelog.rst
index ef26a047..32829ef6 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -21,6 +21,8 @@ Unreleased
 ----------
 
 * :gh:issue:`987` Support Python 3.11
+* :gh:issue:`885` Fix :py:exc:`PermissionError` in :py:mod:`importlib` when
+  becoming an unprivileged user with Python 3.x
 
 
 v0.3.4 (2023-07-02)
diff --git a/mitogen/core.py b/mitogen/core.py
index 707e901a..6a3f3da7 100644
--- a/mitogen/core.py
+++ b/mitogen/core.py
@@ -34,6 +34,34 @@ non-essential code in order to reduce its size, since it is also serves as the
 bootstrap implementation sent to every new slave context.
 """
 
+import sys
+try:
+    import _frozen_importlib_external
+except ImportError:
+    pass
+else:
+    class MonkeyPatchedPathFinder(_frozen_importlib_external.PathFinder):
+        """
+        Meta path finder for sys.path and package __path__ attributes.
+
+        Patched for https://github.com/python/cpython/issues/115911.
+        """
+        @classmethod
+        def _path_importer_cache(cls, path):
+            if path == '':
+                try:
+                    path = _frozen_importlib_external._os.getcwd()
+                except (FileNotFoundError, PermissionError):
+                    return None
+            return super()._path_importer_cache(path)
+
+    if sys.version_info[:2] <= (3, 12):
+        for i, mpf in enumerate(sys.meta_path):
+            if mpf is _frozen_importlib_external.PathFinder:
+                sys.meta_path[i] = MonkeyPatchedPathFinder
+        del i, mpf
+
+
 import binascii
 import collections
 import encodings.latin_1
@@ -49,7 +77,6 @@ import pstats
 import signal
 import socket
 import struct
-import sys
 import syslog
 import threading
 import time
diff --git a/mitogen/parent.py b/mitogen/parent.py
index 1045ddc3..29bcf66d 100644
--- a/mitogen/parent.py
+++ b/mitogen/parent.py
@@ -34,7 +34,7 @@ sent to any child context that is due to become a parent, due to recursive
 connection.
 """
 
-import codecs
+import binascii
 import errno
 import fcntl
 import getpass
@@ -1405,6 +1405,7 @@ class Connection(object):
     # file descriptor 0 as 100, creates a pipe, then execs a new interpreter
     # with a custom argv.
     #   * Optimized for minimum byte count after minification & compression.
+    #     The script preamble_size.py measures this.
     #   * 'CONTEXT_NAME' and 'PREAMBLE_COMPRESSED_LEN' are substituted with
     #     their respective values.
     #   * CONTEXT_NAME must be prefixed with the name of the Python binary in
@@ -1449,7 +1450,7 @@ class Connection(object):
             os.environ['ARGV0']=sys.executable
             os.execl(sys.executable,sys.executable+'(mitogen:CONTEXT_NAME)')
         os.write(1,'MITO000\n'.encode())
-        C=_(os.fdopen(0,'rb').read(PREAMBLE_COMPRESSED_LEN),'zip')
+        C=zlib.decompress(os.fdopen(0,'rb').read(PREAMBLE_COMPRESSED_LEN))
         fp=os.fdopen(W,'wb',0)
         fp.write(C)
         fp.close()
@@ -1481,16 +1482,16 @@ class Connection(object):
         source = source.replace('PREAMBLE_COMPRESSED_LEN',
                                 str(len(preamble_compressed)))
         compressed = zlib.compress(source.encode(), 9)
-        encoded = codecs.encode(compressed, 'base64').replace(b('\n'), b(''))
-        # We can't use bytes.decode() in 3.x since it was restricted to always
-        # return unicode, so codecs.decode() is used instead. In 3.x
-        # codecs.decode() requires a bytes object. Since we must be compatible
-        # with 2.4 (no bytes literal), an extra .encode() either returns the
-        # same str (2.x) or an equivalent bytes (3.x).
+        encoded = binascii.b2a_base64(compressed).replace(b('\n'), b(''))
+
+        # Just enough to decode, decompress, and exec the first stage.
+        # Priorities: wider compatibility, faster startup, shorter length.
+        # `import os` here, instead of stage 1, to save a few bytes.
+        # `sys.path=...` for https://github.com/python/cpython/issues/115911.
         return self.get_python_argv() + [
             '-c',
-            'import codecs,os,sys;_=codecs.decode;'
-            'exec(_(_("%s".encode(),"base64"),"zip"))' % (encoded.decode(),)
+            'import sys;sys.path=[p for p in sys.path if p];import binascii,os,zlib;'
+            'exec(zlib.decompress(binascii.a2b_base64("%s")))' % (encoded.decode(),),
         ]
 
     def get_econtext_config(self):