diff --git a/Lib/getopt.py b/Lib/getopt.py
index 66f4827..251d89c 100644
--- a/Lib/getopt.py
+++ b/Lib/getopt.py
@@ -155,7 +155,7 @@
             if not args:
                 raise GetoptError('option --%s requires argument' % opt, opt)
             optarg, args = args[0], args[1:]
-    elif optarg:
+    elif optarg is not None:
         raise GetoptError('option --%s must not have an argument' % opt, opt)
     opts.append(('--' + opt, optarg or ''))
     return opts, args
diff --git a/Lib/test/test_getopt.py b/Lib/test/test_getopt.py
index 6b18d9f..7186c7f 100644
--- a/Lib/test/test_getopt.py
+++ b/Lib/test/test_getopt.py
@@ -173,6 +173,12 @@
         m = types.ModuleType("libreftest", s)
         run_doctest(m, verbose)
 
+    def test_issue4629(self):
+        longopts, shortopts = getopt.getopt(['--help='], '', ['help='])
+        self.assertEquals(longopts, [('--help', '')])
+        longopts, shortopts = getopt.getopt(['--help=x'], '', ['help='])
+        self.assertEquals(longopts, [('--help', 'x')])
+        self.assertRaises(getopt.GetoptError, getopt.getopt, ['--help='], '', ['help'])
 
 def test_main():
     run_unittest(GetoptTests)