diff --git a/holoviews/plotting/renderer.py b/holoviews/plotting/renderer.py
index e78dba8d98..184c3b03ee 100644
--- a/holoviews/plotting/renderer.py
+++ b/holoviews/plotting/renderer.py
@@ -354,7 +354,7 @@ def export_widgets(self_or_cls, obj, filename, fmt=None, template=None,
             filename.write(encoded)
             filename.seek(0)
         else:
-            with open(filename, 'w') as f:
+            with open(filename, 'wb') as f:
                 f.write(encoded)