diff --git a/plotly/export_fig2/write_image.m b/plotly/export_fig2/write_image.m
index bf84f72..9e88dad 100644
--- a/plotly/export_fig2/write_image.m
+++ b/plotly/export_fig2/write_image.m
@@ -15,6 +15,7 @@
     width=pfObj.layout.width;
     scale=1;
 elseif nargin < 4
+    filename=[filename,'.',char(imageFormat)];
     height=pfObj.layout.height;
     width=pfObj.layout.width;
     scale=1;