diff --git a/bin/generate-exports.py b/bin/generate-exports.py
index 28d7ad6e3d..6e98035ee2 100755
--- a/bin/generate-exports.py
+++ b/bin/generate-exports.py
@@ -52,9 +52,16 @@ class Class(Exportable):
             lines.append(' * @param {%s} options Options.\n' % (self.object_literal.extern_name(),))
             lines.append(' */\n')
             lines.append('%sExport = function(options) {\n' % (self.name,))
-            lines.append('  goog.base(this, {')
-            lines.extend(','.join('\n    %s: options.%s' % (key, key) for key in sorted(self.object_literal.prop_types.keys())))
-            lines.append('\n  });\n')
+            lines.append('  /** @type {%s} */\n' % (self.object_literal.name,))
+            lines.append('  var arg;\n');
+            lines.append('  if (goog.isDefAndNotNull(options)) {\n')
+            lines.append('    arg = {')
+            lines.extend(','.join('\n      %s: options.%s' % (key, key) for key in sorted(self.object_literal.prop_types.keys())))
+            lines.append('\n    };\n')
+            lines.append('  } else {\n')
+            lines.append('    arg = /** @type {%s} */ (options);\n' % (self.object_literal.name,))
+            lines.append('  }\n')
+            lines.append('  goog.base(this, arg);\n')
             lines.append('};\n')
             lines.append('goog.inherits(%sExport, %s);\n' % (self.name, self.name))
             lines.append('goog.exportSymbol(\n')