diff --git a/CMakeLists.txt b/CMakeLists.txt
index b00d443..c369a14 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION "3.14")
 cmake_policy(SET CMP0148 OLD)
-project(Photochem LANGUAGES Fortran C VERSION "0.5.0")
+project(Photochem LANGUAGES Fortran C VERSION "0.5.1")
 
 include(FortranCInterface)
 FortranCInterface_VERIFY()
diff --git a/src/atmosphere/photochem_atmosphere_rhs.f90 b/src/atmosphere/photochem_atmosphere_rhs.f90
index d7e7c17..294f3e4 100644
--- a/src/atmosphere/photochem_atmosphere_rhs.f90
+++ b/src/atmosphere/photochem_atmosphere_rhs.f90
@@ -788,6 +788,8 @@ module subroutine jac_background_gas(self, lda_neqs, neqs, tn, usol_flat, jac, e
     call prep_all_background_gas(self, usol_in, err)
     if (allocated(err)) return
 
+    jac = 0.0_dp
+
     if (.not. var%autodiff) then; block
     real(dp) :: usol_perturb(dat%nq,var%nz)
     real(dp) :: R(var%nz)
@@ -797,7 +799,6 @@ module subroutine jac_background_gas(self, lda_neqs, neqs, tn, usol_flat, jac, e
     ! Finite differenced Jacobian
   
     ! compute chemistry contribution to jacobian using forward differences
-    jac = 0.0_dp
     call dochem(self, var%neqs, dat%nsp, dat%np, dat%nsl, dat%nq, var%nz, var%trop_ind, dat%nrT, &
                 wrk%usol, wrk%density, wrk%rx_rates, &
                 wrk%gas_sat_den, wrk%molecules_per_particle, &
diff --git a/src/evoatmosphere/photochem_evoatmosphere_rhs.f90 b/src/evoatmosphere/photochem_evoatmosphere_rhs.f90
index 7a2810d..d4ec5aa 100644
--- a/src/evoatmosphere/photochem_evoatmosphere_rhs.f90
+++ b/src/evoatmosphere/photochem_evoatmosphere_rhs.f90
@@ -854,6 +854,8 @@ module subroutine jac_evo_gas(self, lda_neqs, neqs, usol_flat, jac, err)
     call prep_all_evo_gas(self, usol_in, err)
     if (allocated(err)) return
   
+    jac = 0.0_dp
+  
     if (.not. var%autodiff) then; block
     real(dp) :: usol_perturb(dat%nq,var%nz)
     real(dp) :: R(var%nz)
@@ -864,7 +866,6 @@ module subroutine jac_evo_gas(self, lda_neqs, neqs, usol_flat, jac, err)
     ! Finite differenced Jacobian
 
     ! compute chemistry contribution to jacobian using forward differences
-    jac = 0.0_dp
     call dochem(self, wrk%usol, wrk%rx_rates, &
                 wrk%gas_sat_den, wrk%molecules_per_particle, &
                 wrk%H2O_sat_mix, wrk%H2O_rh, wrk%rainout_rates, &