diff --git a/vignettes/articles-online-only/opencl.Rmd b/vignettes/articles-online-only/opencl.Rmd
index bc8599efd..838447075 100644
--- a/vignettes/articles-online-only/opencl.Rmd
+++ b/vignettes/articles-online-only/opencl.Rmd
@@ -75,7 +75,7 @@ data {
   int<lower=1> k;
   int<lower=0> n;
   matrix[n, k] X;
-  int y[n];
+  array[n] int y;
 }
 parameters {
   vector[k] beta;