diff --git a/plotly/plotly/plotly.py b/plotly/plotly/plotly.py
index 0e374b518e1..04fa7fc6b3c 100644
--- a/plotly/plotly/plotly.py
+++ b/plotly/plotly/plotly.py
@@ -660,7 +660,7 @@ def save_as(cls, figure_or_data, filename, format=None, width=None, height=None)
             format = ext[1:]
         elif not ext and format:
             filename += '.'+format
-        else:
+        elif ext[1:].lower() != format.lower():
             filename += '.'+format
 
         img = cls.get(figure_or_data, format, width, height)