diff --git a/demos_ch11/demo11_5.R b/demos_ch11/demo11_5.R
index d82cb37..b019009 100644
--- a/demos_ch11/demo11_5.R
+++ b/demos_ch11/demo11_5.R
@@ -11,7 +11,7 @@
 #+ setup, message=FALSE, error=FALSE, warning=FALSE
 library(posterior)
 library(bayesplot)
-theme_set(bayesplot::theme_default(base_family = "sans"))
+ggplot2::theme_set(bayesplot::theme_default(base_family = "sans"))
 
 #' ## Use of posterior package for convergence diagnostics
 #' 
diff --git a/demos_ch11/demo11_5.Rmd b/demos_ch11/demo11_5.Rmd
index 7344d4f..b55088b 100644
--- a/demos_ch11/demo11_5.Rmd
+++ b/demos_ch11/demo11_5.Rmd
@@ -11,7 +11,7 @@ output:
 ```{r setup, message=FALSE, error=FALSE, warning=FALSE}
 library(posterior)
 library(bayesplot)
-theme_set(bayesplot::theme_default(base_family = "sans"))
+ggplot2::theme_set(bayesplot::theme_default(base_family = "sans"))
 ```
 
 ## Use of posterior package for convergence diagnostics