diff --git a/src/stan/analyze/mcmc/mcse.hpp b/src/stan/analyze/mcmc/mcse.hpp
index 040b94d9ea..b859cfa32c 100644
--- a/src/stan/analyze/mcmc/mcse.hpp
+++ b/src/stan/analyze/mcmc/mcse.hpp
@@ -21,7 +21,6 @@ namespace analyze {
  * @return mcse
  */
 inline double mcse_mean(const Eigen::MatrixXd& chains) {
-  const Eigen::Index num_draws = chains.rows();
   if (chains.rows() < 4 || !is_finite_and_varies(chains))
     return std::numeric_limits<double>::quiet_NaN();