diff --git a/Lib/importlib/__init__.py b/Lib/importlib/__init__.py
index f6adc5c..1bc9947 100644
--- a/Lib/importlib/__init__.py
+++ b/Lib/importlib/__init__.py
@@ -22,7 +22,12 @@
     # a second copy of the module.
     _bootstrap.__name__ = 'importlib._bootstrap'
     _bootstrap.__package__ = 'importlib'
-    _bootstrap.__file__ = __file__.replace('__init__.py', '_bootstrap.py')
+    try:
+        _bootstrap.__file__ = __file__.replace('__init__.py', '_bootstrap.py')
+    except NameError:
+        # __file__ is not guaranteed to be defined, e.g. if this code gets
+        # frozen by a tool like cx_Freeze.
+        pass
     sys.modules['importlib._bootstrap'] = _bootstrap
 
 # To simplify imports in test code
diff --git a/Misc/NEWS b/Misc/NEWS
index 33e7092..ab25f1a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -21,6 +21,8 @@
 Library
 -------
 
+- Issue #20884: Don't assume that __file__ is defined on importlib.__init__.
+
 - Issue #20879: Delay the initialization of encoding and decoding tables for
   base32, ascii85 and base85 codecs in the base64 module, and delay the
   initialization of the unquote_to_bytes() table of the urllib.parse module, to