diff --git a/Lib/os.py b/Lib/os.py
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -61,6 +61,10 @@
     except ImportError:
         pass
 
+    import posix
+    __all__.extend(_get_exports_list(posix))
+    del posix
+
 elif 'nt' in _names:
     name = 'nt'
     linesep = '\r\n'
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -2252,6 +2252,13 @@
         else:
             self.skipTest("Could not determine the number of CPUs")
 
+
+class ExportsTests(unittest.TestCase):
+    def test_os_all(self):
+        self.assertIn('open', os.__all__)
+        self.assertIn('walk', os.__all__)
+
+
 @support.reap_threads
 def test_main():
     support.run_unittest(
@@ -2284,6 +2291,7 @@
         OSErrorTests,
         RemoveDirsTests,
         CPUCountTests,
+        ExportsTests,
     )
 
 if __name__ == "__main__":