diff --git a/src/CartBlock.C b/src/CartBlock.C
index b4c58d0..8b21f80 100644
--- a/src/CartBlock.C
+++ b/src/CartBlock.C
@@ -22,6 +22,8 @@
 #include <algorithm>
 #include <cassert>
 #include <cmath>
+#include <cstddef>
+#include <limits>
 #include "TiogaMeshInfo.h"
 #include "codetypes.h"
 #include "CartBlock.h"
@@ -30,7 +32,6 @@
 #include "linCartInterp.h"
 #include "linklist.h"
 #include "tioga_utils.h"
-#include <limits>
 
 void CartBlock::registerData(int lid, TIOGA::AMRMeshInfo* minfo)
 {
@@ -112,7 +113,8 @@ void CartBlock::getInterpolatedData(
 
             for (i = 0; i < listptr->nweights; i++) {
                 int const cell_index = (cart_utils::get_cell_index(
-                    dims[0], dims[1], nf, listptr->inode[3 * i],
+                    dims[0], dims[1], nf,
+                    listptr->inode[static_cast<ptrdiff_t>(3 * i)],
                     listptr->inode[(3 * i) + 1], listptr->inode[(3 * i) + 2]));
                 for (n = 0; n < nvar_cell; n++) {
                     weight = listptr->weights[i];
@@ -169,7 +171,8 @@ void CartBlock::preprocess(CartGrid* cg)
     for (int n = 0; n < 3; n++) {
         dx[n] = cg->dx[(3 * global_id) + n];
     }
-    dims[0] = cg->ihi[3 * global_id] - cg->ilo[3 * global_id] + 1;
+    dims[0] = cg->ihi[static_cast<ptrdiff_t>(3 * global_id)] -
+              cg->ilo[static_cast<ptrdiff_t>(3 * global_id)] + 1;
     dims[1] = cg->ihi[(3 * global_id) + 1] - cg->ilo[(3 * global_id) + 1] + 1;
     dims[2] = cg->ihi[(3 * global_id) + 2] - cg->ilo[(3 * global_id) + 2] + 1;
     nf = cg->nf;
diff --git a/src/CartGrid.C b/src/CartGrid.C
index 0027452..308258a 100644
--- a/src/CartGrid.C
+++ b/src/CartGrid.C
@@ -23,6 +23,7 @@
 #include <cmath>
 #include <numeric>
 #include <limits>
+#include <cstddef>
 
 #include "tioga_gpu.h"
 #include "TiogaMeshInfo.h"
@@ -221,17 +222,19 @@ void CartGrid::search(double* x, int* donorid, int npts)
                 }
             }
         }
-        if (myid == 2 && abs(x[3 * i] - 0.739573) < 1e-5 &&
+        if (myid == 2 &&
+            abs(x[static_cast<ptrdiff_t>(3 * i)] - 0.739573) < 1e-5 &&
             abs(x[(3 * i) + 1] + 0.259310) < 1e-5 &&
             abs(x[(3 * i) + 2] + 0.639614) < 1e-5) {
             printf(
-                "%d %d %f %f %f %d\n", myid, i, x[3 * i], x[(3 * i) + 1],
+                "%d %d %f %f %f %d\n", myid, i,
+                x[static_cast<ptrdiff_t>(3 * i)], x[(3 * i) + 1],
                 x[(3 * i) + 2], donorid[i]);
         }
         if (donorid[i] == -1) {
             printf(
-                "%d %f %f %f\n", myid, x[3 * i], x[(3 * i) + 1],
-                x[(3 * i) + 2]);
+                "%d %f %f %f\n", myid, x[static_cast<ptrdiff_t>(3 * i)],
+                x[(3 * i) + 1], x[(3 * i) + 2]);
         }
     }
     // printf("CartGrid::search Processor %d located %d of %d
diff --git a/src/MeshBlock.C b/src/MeshBlock.C
index 1c99aa6..24a8d0b 100644
--- a/src/MeshBlock.C
+++ b/src/MeshBlock.C
@@ -988,7 +988,8 @@ void MeshBlock::writeFlowFile(int bid, double* q, int nvar, int type)
         for (i = 0; i < nc[n]; i++) {
             if (nvert == 4) {
                 fprintf(
-                    fp, "%d %d %d %d %d %d %d %d\n", vconn[n][nvert * i] + ba,
+                    fp, "%d %d %d %d %d %d %d %d\n",
+                    vconn[n][static_cast<ptrdiff_t>(nvert * i)] + ba,
                     vconn[n][(nvert * i) + 1] + ba,
                     vconn[n][(nvert * i) + 2] + ba,
                     vconn[n][(nvert * i) + 2] + ba,
@@ -1008,7 +1009,8 @@ void MeshBlock::writeFlowFile(int bid, double* q, int nvar, int type)
                     vconn[n][(nvert * i) + 4] + ba);
             } else if (nvert == 6) {
                 fprintf(
-                    fp, "%d %d %d %d %d %d %d %d\n", vconn[n][nvert * i] + ba,
+                    fp, "%d %d %d %d %d %d %d %d\n",
+                    vconn[n][static_cast<ptrdiff_t>(nvert * i)] + ba,
                     vconn[n][(nvert * i) + 1] + ba,
                     vconn[n][(nvert * i) + 2] + ba,
                     vconn[n][(nvert * i) + 2] + ba,
@@ -1018,7 +1020,8 @@ void MeshBlock::writeFlowFile(int bid, double* q, int nvar, int type)
                     vconn[n][(nvert * i) + 5] + ba);
             } else if (nvert == 8) {
                 fprintf(
-                    fp, "%d %d %d %d %d %d %d %d\n", vconn[n][nvert * i] + ba,
+                    fp, "%d %d %d %d %d %d %d %d\n",
+                    vconn[n][static_cast<ptrdiff_t>(nvert * i)] + ba,
                     vconn[n][(nvert * i) + 1] + ba,
                     vconn[n][(nvert * i) + 2] + ba,
                     vconn[n][(nvert * i) + 3] + ba,