diff --git a/backtrader_plotting/bokeh/bokeh.py b/backtrader_plotting/bokeh/bokeh.py
index f63abb0..3ec1d22 100644
--- a/backtrader_plotting/bokeh/bokeh.py
+++ b/backtrader_plotting/bokeh/bokeh.py
@@ -414,7 +414,7 @@ def _output_plot_file(self, model, idx, filename=None, template="basic.html.j2")
                              )
                          )
 
-        with open(filename, 'w') as f:
+        with open(filename, 'w', encoding='utf-8') as f:
             f.write(html)
 
         return filename