diff --git a/assets/header-lab.Rmd b/assets/header-lab.Rmd
index f3c9f984..5bf411c8 100644
--- a/assets/header-lab.Rmd
+++ b/assets/header-lab.Rmd
@@ -16,6 +16,9 @@ htmltools::tagList(fa)
 tc <- captioner::captioner(prefix="<b>Tab. </b>")
 fc <- captioner::captioner(prefix="<b>Fig. </b>")
 
+# turn off terminal colors
+options(crayon.enabled = FALSE)
+
 # knitr options
 knitr::opts_knit$set(progress=TRUE,verbose=TRUE)
 knitr::opts_chunk$set(dev="svg",results="hold",fig.show="hold",fig.align="left",
diff --git a/assets/header-slide.Rmd b/assets/header-slide.Rmd
index dd9a32e9..90beb27e 100644
--- a/assets/header-slide.Rmd
+++ b/assets/header-slide.Rmd
@@ -18,6 +18,9 @@ library(bookdown) # for markdown
 color_primary <- "#4C979F"
 color_text <- "#424949"
 
+# turn off terminal colors
+options(crayon.enabled = FALSE)
+
 # knitr options
 knitr::opts_knit$set(progress=TRUE,verbose=TRUE)
 knitr::opts_chunk$set(dev="svg",results="hold",fig.show="hold",fig.align="left",echo=TRUE,warning=FALSE,message=FALSE)