diff --git a/src/mptrac.c b/src/mptrac.c
index 6fdb0e8a9..f2735d856 100644
--- a/src/mptrac.c
+++ b/src/mptrac.c
@@ -2455,7 +2455,7 @@ void module_chemgrid(
   double *restrict const press =
     (double *) malloc((size_t) nz * sizeof(double));
   double *restrict const mass =
-    (double *) malloc((size_t) ngrid * sizeof(double));
+    (double *) calloc((size_t) ngrid, sizeof(double));
   double *restrict const area =
     (double *) malloc((size_t) ny * sizeof(double));
   double *restrict const lon =
@@ -2472,10 +2472,6 @@ void module_chemgrid(
   const double dlon = (ctl->chemgrid_lon1 - ctl->chemgrid_lon0) / nx;
   const double dlat = (ctl->chemgrid_lat1 - ctl->chemgrid_lat0) / ny;
 
-  /* Initialize mass... */// TODO: does not work on GPU?
-  for (int i = 0; i < ngrid; i++)
-    mass[i] = 0;
-
   /* Set vertical coordinates... */
 #ifdef _OPENACC
 #pragma acc enter data create(ixs[0:np],iys[0:np],izs[0:np],z[0:nz],press[0:nz],mass[0:ngrid],area[0:ny],lon[0:nx],lat[0:ny])
@@ -2505,8 +2501,7 @@ void module_chemgrid(
     izs[ip] = (int) ((Z(atm->p[ip]) - ctl->chemgrid_z0) / dz);
     if (atm->time[ip] < t0 || atm->time[ip] > t1
 	|| ixs[ip] < 0 || ixs[ip] >= nx
-	|| iys[ip] < 0 || iys[ip] >= ny
-	|| izs[ip] < 0 || izs[ip] >= nz)
+	|| iys[ip] < 0 || iys[ip] >= ny || izs[ip] < 0 || izs[ip] >= nz)
       izs[ip] = -1;
   }
 
diff --git a/src/trac.c b/src/trac.c
index c8b96f91c..1384e7267 100644
--- a/src/trac.c
+++ b/src/trac.c
@@ -287,7 +287,7 @@ int main(
 	  if (ctl.oh_chem_reaction != 0 || ctl.h2o2_chem_reaction != 0
 	      || (ctl.kpp_chem && fmod(t, ctl.dt_kpp) == 0))
 	    module_chemgrid(&ctl, met0, met1, atm, t);
-	  
+
 	  /* OH chemistry... */
 	  if (ctl.oh_chem_reaction != 0)
 	    module_oh_chem(&ctl, clim, met0, met1, atm, dt);