diff --git a/models/BGKModel.cpp b/models/BGKModel.cpp
index d2aa5216..25b3a49e 100644
--- a/models/BGKModel.cpp
+++ b/models/BGKModel.cpp
@@ -215,8 +215,8 @@ void ScaLBL_BGKModel::Create() {
     if (rank == 0)
         printf("Allocating distributions \n");
     //......................device distributions.................................
-    int dist_mem_size = Np * sizeof(double);
-    int neighborSize = 18 * (Np * sizeof(int));
+    size_t dist_mem_size = Np * sizeof(double);
+    size_t neighborSize = 18 * (Np * sizeof(int));
     //...........................................................................
     ScaLBL_AllocateDeviceMemory((void **)&NeighborList, neighborSize);
     ScaLBL_AllocateDeviceMemory((void **)&fq, 19 * dist_mem_size);
diff --git a/models/ColorModel.h b/models/ColorModel.h
index 7089c619..888f4fc2 100644
--- a/models/ColorModel.h
+++ b/models/ColorModel.h
@@ -154,8 +154,8 @@ public:
 private:
     Utilities::MPI comm;
 
-    int dist_mem_size;
-    int neighborSize;
+    size_t dist_mem_size;
+    size_t neighborSize;
     // filenames
     char LocalRankString[8];
     char LocalRankFilename[40];
diff --git a/models/DFHModel.h b/models/DFHModel.h
index d9509568..8fe1a0c3 100644
--- a/models/DFHModel.h
+++ b/models/DFHModel.h
@@ -68,8 +68,8 @@ public:
 private:
     Utilities::MPI comm;
 
-    int dist_mem_size;
-    int neighborSize;
+    size_t dist_mem_size;
+    size_t neighborSize;
     // filenames
     char LocalRankString[8];
     char LocalRankFilename[40];
diff --git a/models/FreeLeeModel.h b/models/FreeLeeModel.h
index 3a690a3c..b1fd5905 100644
--- a/models/FreeLeeModel.h
+++ b/models/FreeLeeModel.h
@@ -91,8 +91,8 @@ public:
 private:
     Utilities::MPI comm;
 
-    int dist_mem_size;
-    int neighborSize;
+    size_t dist_mem_size;
+    size_t neighborSize;
     // filenames
     char LocalRankString[8];
     char LocalRankFilename[40];
diff --git a/models/GreyscaleColorModel.h b/models/GreyscaleColorModel.h
index 0c183f8a..631bfb51 100644
--- a/models/GreyscaleColorModel.h
+++ b/models/GreyscaleColorModel.h
@@ -133,8 +133,8 @@ public:
 private:
     Utilities::MPI comm;
 
-    int dist_mem_size;
-    int neighborSize;
+    size_t dist_mem_size;
+    size_t neighborSize;
     // filenames
     char LocalRankString[8];
     char LocalRankFilename[40];
diff --git a/models/GreyscaleModel.h b/models/GreyscaleModel.h
index 9feff45f..c61b1746 100644
--- a/models/GreyscaleModel.h
+++ b/models/GreyscaleModel.h
@@ -93,8 +93,8 @@ public:
 private:
     Utilities::MPI comm;
 
-    int dist_mem_size;
-    int neighborSize;
+    size_t dist_mem_size;
+    size_t neighborSize;
     // filenames
     char LocalRankString[8];
     char LocalRankFilename[40];
diff --git a/models/MRTModel.cpp b/models/MRTModel.cpp
index 67444f8f..a22b5c9a 100644
--- a/models/MRTModel.cpp
+++ b/models/MRTModel.cpp
@@ -220,8 +220,8 @@ void ScaLBL_MRTModel::Create() {
     if (rank == 0)
         printf("Allocating distributions \n");
     //......................device distributions.................................
-    int dist_mem_size = Np * sizeof(double);
-    int neighborSize = 18 * (Np * sizeof(int));
+    size_t dist_mem_size = Np * sizeof(double);
+    size_t neighborSize = 18 * (Np * sizeof(int));
     //...........................................................................
     ScaLBL_AllocateDeviceMemory((void **)&NeighborList, neighborSize);
     ScaLBL_AllocateDeviceMemory((void **)&fq, 19 * dist_mem_size);
diff --git a/models/StokesModel.cpp b/models/StokesModel.cpp
index 2098be5f..e0ae8ba2 100644
--- a/models/StokesModel.cpp
+++ b/models/StokesModel.cpp
@@ -516,8 +516,8 @@ void ScaLBL_StokesModel::Create() {
     if (rank == 0)
         printf("LB Single-Fluid Solver: Allocating distributions \n");
     //......................device distributions.................................
-    int dist_mem_size = Np * sizeof(double);
-    int neighborSize = 18 * (Np * sizeof(int));
+    size_t dist_mem_size = Np * sizeof(double);
+    size_t neighborSize = 18 * (Np * sizeof(int));
     //...........................................................................
     ScaLBL_AllocateDeviceMemory((void **)&NeighborList, neighborSize);
     ScaLBL_AllocateDeviceMemory((void **)&fq, 19 * dist_mem_size);