diff --git a/R/utilities.R b/R/utilities.R
index 0cc57532..ca55175a 100644
--- a/R/utilities.R
+++ b/R/utilities.R
@@ -574,12 +574,12 @@ get_stan_model <- function() {
     cache_dir <- getOption("rbmi.cache_dir")
     dir.create(cache_dir, showWarnings = FALSE, recursive = TRUE)
     model_file <- file.path(cache_dir, paste0("MMRM_", get_session_hash(), ".stan"))
-    
+
     if (!file.exists(model_file)) {
         clear_model_cache()
         file.copy(file_loc, model_file, overwrite = TRUE)
     }
-    
+
     rstan::stan_model(
         file = model_file,
         auto_write = TRUE,
@@ -603,8 +603,18 @@ get_stan_model <- function() {
 #'
 #' Default = `tools::R_user_dir("rbmi", which = "cache")`
 #'
-#' Directory to store compiled Stan model in. If not set, a temporary directory is used for
-#' the given R session. Can also be set via the environment variable `RBMI_CACHE_DIR`.
+#' Directory to store compiled Stan models in to avoid having to re-compile.
+#' If the environment variable `RBMI_CACHE_DIR` has been set this will be used
+#' as the default value.
+#' Note that if you are running rbmi in multiple R processes at the same time
+#' (that is say multiple calls to `Rscript` at once) then there is a theoretical
+#' risk of the processes breaking each other as they attempt to read/write to the
+#' same cache folder at the same time. To avoid this potential issue it is recommended
+#' to set the cache directory to a unique folder for each R session e.g.
+#'
+#' ```
+#' options("rbmi.cache_dir" = tempdir(check = TRUE))
+#' ```
 #'
 #'
 #' @examples
diff --git a/man/rbmi-settings.Rd b/man/rbmi-settings.Rd
index de28d650..d9ffc6cd 100644
--- a/man/rbmi-settings.Rd
+++ b/man/rbmi-settings.Rd
@@ -18,8 +18,17 @@ Each of the following are the name of options that can be set via:
 
 Default = \code{tools::R_user_dir("rbmi", which = "cache")}
 
-Directory to store compiled Stan model in. If not set, a temporary directory is used for
-the given R session. Can also be set via the environment variable \code{RBMI_CACHE_DIR}.
+Directory to store compiled Stan models in to avoid having to re-compile.
+If the environment variable \code{RBMI_CACHE_DIR} has been set this will be used
+as the default value.
+Note that if you are running rbmi in multiple R processes at the same time
+(that is say multiple calls to \code{Rscript} at once) then there is a theoretical
+risk of the processes breaking each other as they attempt to read/write to the
+same cache folder at the same time. To avoid this potential issue it is recommended
+to set the cache directory to a unique folder for each R session e.g.
+
+\if{html}{\out{<div class="sourceCode">}}\preformatted{options("rbmi.cache_dir" = tempdir(check = TRUE))
+}\if{html}{\out{</div>}}
 }
 }
 \examples{