diff --git a/DESCRIPTION b/DESCRIPTION
index 0f004b5..ca004c4 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -25,7 +25,7 @@ Imports:
     ggplot2 (>= 3.3.2),
     metRology (>= 0.9.28.1),
     reshape (>= 0.8.8),
-    rstan (>= 2.21.2),
+    rstan (>= 2.26.0),
     rstantools (>= 2.1.1),
     mcmcse (>= 1.4.1),
     stats (>= 4.0.0),
@@ -35,8 +35,8 @@ Suggests:
     rmarkdown (>= 2.5.0),
     knitr (>= 1.30.0)
 LinkingTo:
-    StanHeaders (>= 2.21.0.6),
-    rstan (>= 2.21.0),
+    StanHeaders (>= 2.26.0),
+    rstan (>= 2.26.0),
     BH (>= 1.72.0.3),
     Rcpp (>= 1.0.5),
     RcppEigen (>= 0.3.3.7.0),
diff --git a/inst/stan/color.stan b/inst/stan/color.stan
index 0694169..47da54b 100644
--- a/inst/stan/color.stan
+++ b/inst/stan/color.stan
@@ -1,17 +1,17 @@
 data {
 	int<lower=0> n; // number of data entries
 	// rgb
-	real<lower=0,upper=255> r[n];
-	real<lower=0,upper=255> g[n];
-	real<lower=0,upper=255> b[n];
+	array[n] real<lower=0,upper=255> r;
+	array[n] real<lower=0,upper=255> g;
+	array[n] real<lower=0,upper=255> b;
 	// hsv
-	real<lower=0,upper=2*pi()> h[n];
-	real<lower=0,upper=1> s[n];
-	real<lower=0,upper=1> v[n];
+	array[n] real<lower=0,upper=2*pi()> h;
+	array[n] real<lower=0,upper=1> s;
+	array[n] real<lower=0,upper=1> v;
 
 	// priors
-	int<lower=0> p_ids[12];
-	real p_values[24];
+	array[12] int<lower=0> p_ids;
+	array[24] real p_values;
 }
 
 parameters {
diff --git a/inst/stan/linear.stan b/inst/stan/linear.stan
index 8d4a43d..c6d746d 100644
--- a/inst/stan/linear.stan
+++ b/inst/stan/linear.stan
@@ -3,11 +3,11 @@ data {
   int<lower=0> m; // number of subjects
   vector[n] x; // sequence/time
   vector[n] y; // response
-  int<lower=0> s[n]; // subject ids
+  array[n] int<lower=0> s; // subject ids
 
   // priors
-  int<lower=0> p_ids[6];
-  real p_values[12];
+  array[6] int<lower=0> p_ids;
+  array[12] real p_values;
 }
 
 parameters {
diff --git a/inst/stan/reaction_time.stan b/inst/stan/reaction_time.stan
index b1dad16..01efcb5 100644
--- a/inst/stan/reaction_time.stan
+++ b/inst/stan/reaction_time.stan
@@ -2,11 +2,11 @@ data {
   int<lower=0> n; // total number of measurements
   int<lower=0> m; // number of subjects
   vector<lower=0>[n] t; // reaction times
-  int<lower=0> s[n]; // subject ids
+  array[n] int<lower=0> s; // subject ids
 
   // priors
-  int p_ids[6];
-  real p_values[12];
+  array[6] int p_ids;
+  array[12] real p_values;
 }
 
 parameters {
diff --git a/inst/stan/success_rate.stan b/inst/stan/success_rate.stan
index db6f437..760c18c 100644
--- a/inst/stan/success_rate.stan
+++ b/inst/stan/success_rate.stan
@@ -1,12 +1,12 @@
 data {
   int<lower=0> n; // total number of measurements
   int<lower=0> m; // number of subjects
-  int<lower=0,upper=1> r[n]; // results - success or fail
-  int<lower=0> s[n]; // subject ids
+  array[n] int<lower=0,upper=1> r; // results - success or fail
+  array[n] int<lower=0> s; // subject ids
 
   // priors
-  int<lower=0> p_ids[2];
-  real<lower=0> p_values[4];
+  array[2] int<lower=0> p_ids;
+  array[4] real<lower=0> p_values;
 }
 
 parameters {
diff --git a/inst/stan/ttest.stan b/inst/stan/ttest.stan
index a94adcf..28a7fe2 100644
--- a/inst/stan/ttest.stan
+++ b/inst/stan/ttest.stan
@@ -1,10 +1,10 @@
 data {
   int<lower=0> n; // number of samples
-  real y[n];
+  array[n] real y;
 
   // priors
-  int<lower=0> p_ids[3];
-  real p_values[6];
+  array[3] int<lower=0> p_ids;
+  array[6] real p_values;
 }
 
 parameters {