diff --git a/R/dynamite.R b/R/dynamite.R
index 33ac3fb..9c94bfa 100644
--- a/R/dynamite.R
+++ b/R/dynamite.R
@@ -237,12 +237,7 @@ dynamite <- function(dformula, data, time, group = NULL,
   # copy so that get_data can still return the full stan_input via debug
   stan_input_out <- stan_input
   stan_input_out$sampling_vars <- NULL
-  n_draws <- ifelse_(
-    is.null(stanfit),
-    0L,
-    (stanfit@sim$n_save[1L] - stanfit@sim$warmup2[1L]) *
-      stanfit@sim$chains
-  )
+  n_draws <- ifelse_(is.null(stanfit), 0L, get_ndraws(stanfit))
   out <- structure(
     list(
       stanfit = stanfit,
diff --git a/R/stan_utilities.R b/R/stan_utilities.R
index 301a393..8bd6d1b 100644
--- a/R/stan_utilities.R
+++ b/R/stan_utilities.R
@@ -225,7 +225,7 @@ get_diagnostics.stanfit <- function(x) {
 }
 
 get_diagnostics.CmdStanMCMC <- function(x) {
-  x$diagnostic_summary(x)
+  x$diagnostic_summary()
 }
 
 get_max_treedepth.stanfit <- function(x) {
@@ -256,7 +256,7 @@ get_draws.stanfit <- function(x, pars) {
 }
 
 get_draws.CmdStanMCMC <- function(x, pars) {
-  x$draws(varibles = pars)
+  x$draws(variables = pars)
 }
 
 get_elapsed_time.stanfit <- function(x) {