diff --git a/vignettes/survival-data-with-a-constant-baseline-hazard.Rmd b/vignettes/survival-data-with-a-constant-baseline-hazard.Rmd
index 9def985..198f5c7 100644
--- a/vignettes/survival-data-with-a-constant-baseline-hazard.Rmd
+++ b/vignettes/survival-data-with-a-constant-baseline-hazard.Rmd
@@ -9,7 +9,7 @@ vignette: >
   %\VignetteEncoding{UTF-8}
 ---
 
-```r
+```{r setup, include = FALSE}
 knitr::opts_chunk$set(
   collapse = TRUE,
   comment = "#>"
diff --git a/vignettes/survival-data-with-age-specific-baseline-hazard.Rmd b/vignettes/survival-data-with-age-specific-baseline-hazard.Rmd
index 015d658..40c32d2 100644
--- a/vignettes/survival-data-with-age-specific-baseline-hazard.Rmd
+++ b/vignettes/survival-data-with-age-specific-baseline-hazard.Rmd
@@ -9,7 +9,7 @@ vignette: >
   %\VignetteEncoding{UTF-8}
 ---
 
-```r
+```{r setup, include = FALSE}
 knitr::opts_chunk$set(
   collapse = TRUE,
   comment = "#>"