diff --git a/networks/primordial_chem/actual_rhs.H b/networks/primordial_chem/actual_rhs.H
index aa740f7e38..62003b3370 100644
--- a/networks/primordial_chem/actual_rhs.H
+++ b/networks/primordial_chem/actual_rhs.H
@@ -1202,7 +1202,7 @@ Real rhs_eint(const burn_t& state,
 
 
 AMREX_GPU_HOST_DEVICE AMREX_INLINE
-void actual_rhs (burn_t& state, Array1D<Real, 1, neqs>& ydot)
+void actual_rhs (const burn_t& state, Array1D<Real, 1, neqs>& ydot)
 {
     Real z = redshift;