diff --git a/vignettes/quantiles.qmd b/vignettes/quantiles.qmd
index 59a4a12..9a1e63d 100644
--- a/vignettes/quantiles.qmd
+++ b/vignettes/quantiles.qmd
@@ -17,15 +17,16 @@ vignette: >
 ---
 
 ```{r preliminaries, echo=FALSE, message=FALSE, results="hide"}
-pkg_installer <- get("install.packages")
 if(!("gamlss.ggplots" %in% installed.packages()) || packageVersion("gamlss.ggplots") < "2.1-15") {
-  pkg_installer("gamlss.ggplots", repos = "https://gamlss-dev.R-universe.dev")
+  install.packages("gamlss.ggplots", repos = "https://gamlss-dev.R-universe.dev")
 }
 
 if(packageVersion("gamlss.dist") < "6.1-3") {
-  pkg_installer("gamlss.dist", repos = "https://gamlss-dev.R-universe.dev")
+  install.packages("gamlss.dist", repos = "https://gamlss-dev.R-universe.dev")
 }
 
+dev_version <- packageVersion("gamlss.ggplots") >= "2.1-15" && packageVersion("gamlss.dist") >= "6.1-3"
+
 library("gamlss2")
 ```
 
@@ -136,12 +137,14 @@ Our preferred approach is to use the `resid_wp()` function from the `gamlss.ggpl
 as it provides additional useful information.
 
 ```{r}
+#| eval: !expr 'dev_version'
 #| message: false
 library("gamlss.ggplots")
 resid_wp(m3)
 ```
 The function `model_wp()` can be use for multiple model worm plots.  
 ```{r}
+#| eval: !expr 'dev_version'
 #| message: false
 model_wp(m1, m2, m3)
 ```
@@ -151,6 +154,7 @@ into different age ranges, which is useful for detecting model inadequacies acro
 age groups. Here' s how you can use the `model_wp_wrap()` function:
     
 ```{r}
+#| eval: !expr 'dev_version'
 #| message: false
 model_wp_wrap(m1,m2,m3,xvar=dbbmi$age)
 ```
@@ -187,6 +191,7 @@ A more elegant plot can be generated using the `fitted_centiles()` or `fitted_ce
 functions from the `gamlss.ggplots` package. For example:
 
 ```{r}
+#| eval: !expr 'dev_version'
 #| warning: false   
 fitted_centiles_legend(m3, cent= c(2, 10, 25, 50, 75, 90, 98))
 ```