diff --git a/pyqtgraph/graphicsItems/GradientEditorItem.py b/pyqtgraph/graphicsItems/GradientEditorItem.py
index 6ce06b61..f359ff11 100644
--- a/pyqtgraph/graphicsItems/GradientEditorItem.py
+++ b/pyqtgraph/graphicsItems/GradientEditorItem.py
@@ -27,7 +27,8 @@ Gradients = OrderedDict([
 def addGradientListToDocstring():
     """Decorator to add list of current pre-defined gradients to the end of a function docstring."""
     def dec(fn):
-        fn.__doc__ = fn.__doc__ + str(Gradients.keys()).strip('[').strip(']')
+        if fn.__doc__ is not None:
+            fn.__doc__ = fn.__doc__ + str(Gradients.keys()).strip('[').strip(']')
         return fn
     return dec