diff --git a/src/stan/mcmc/hmc/hamiltonians/diag_e_metric.hpp b/src/stan/mcmc/hmc/hamiltonians/diag_e_metric.hpp
index ba895082602..ccc0b8d3346 100644
--- a/src/stan/mcmc/hmc/hamiltonians/diag_e_metric.hpp
+++ b/src/stan/mcmc/hmc/hamiltonians/diag_e_metric.hpp
@@ -46,7 +46,7 @@ class diag_e_metric : public base_hamiltonian<Model, diag_e_point, BaseRNG> {
         rand_diag_gaus(rng, boost::normal_distribution<>());
 
     z.p = z.get_inv_metric().unaryExpr(
-        [&](auto&& x) { return rand_diag_gaus() / sqrt(x); });
+        [&rand_diag_gaus](auto&& x) { return rand_diag_gaus() / sqrt(x); });
   }
 };