diff --git a/backtesting/backtesting.py b/backtesting/backtesting.py
index 8e835082..9beb93f3 100644
--- a/backtesting/backtesting.py
+++ b/backtesting/backtesting.py
@@ -1735,7 +1735,7 @@ def plot(self, *, results: pd.Series = None, filename=None, plot_width=None,
 
 __all__ = [getattr(v, '__name__', k)
            for k, v in globals().items()                        # export
-           if ((callable(v) and v.__module__ == __name__ or     # callables from this module
+           if ((callable(v) and getattr(v, '__module__', None) == __name__ or  # callables from this module; getattr for Python 3.9; # noqa: E501
                 k.isupper()) and                                # or CONSTANTS
                not getattr(v, '__name__', k).startswith('_'))]  # neither marked internal