diff --git a/index.Rmd b/index.Rmd
index 81ae14315..d51cea1e7 100755
--- a/index.Rmd
+++ b/index.Rmd
@@ -65,7 +65,7 @@ opts_chunk$set(
   comment = NA,
   fig.pos = 'H',
   fig.retina = 1,
-  fig.width = 6,
+  fig.width = if(knitr::is_html_output()) "6",
   fig.asp = if(knitr::is_html_output()) "2/3"
 )
 ```