diff --git a/Src/Components/FTestCell.hpp b/Src/Components/FTestCell.hpp
index fa9a29be6254394953e423b0d43269164404b106..5187edea03032e4f76497d0204340970bd83db8a 100755
--- a/Src/Components/FTestCell.hpp
+++ b/Src/Components/FTestCell.hpp
@@ -16,6 +16,7 @@
 #ifndef FTESTCELL_HPP
 #define FTESTCELL_HPP
 
+#include <cstddef>
 #include "FBasicCell.hpp"
 
 /**
@@ -75,7 +76,7 @@ public:
         buffer >> dataDown >> dataUp;
     }
 
-  static int GetSize(){
+  static size_t GetSize(){
     return sizeof(long long int)*2;
   }
 
diff --git a/UTests/utestBuffer.cpp b/UTests/utestBuffer.cpp
index e04ffd2109e75a3b47d9723117b21378821dfe1a..ac1bdd389da215536bce30964b3f2de190a900ed 100755
--- a/UTests/utestBuffer.cpp
+++ b/UTests/utestBuffer.cpp
@@ -13,6 +13,9 @@
 // "http://www.cecill.info". 
 // "http://www.gnu.org/licenses".
 // ===================================================================================
+#
+#include <cstddef>
+
 #include "FUTester.hpp"
 
 #include "../Src/Containers/FBufferReader.hpp"
@@ -27,7 +30,7 @@ class TestBuffer : public FUTester<TestBuffer> {
         void TestWriteRead(){
             FBufferWriter writer;
 
-            const int BytesTested = (sizeof(int)+sizeof(char)+sizeof(double)+sizeof(float));
+            const int BytesTested = static_cast<int>(sizeof(int)+sizeof(char)+sizeof(double)+sizeof(float));
             const int NbTest = 5;
             for(int idxWrite = 0 ; idxWrite < NbTest ; ++idxWrite){
                 writer << idxWrite << char(idxWrite) << double(idxWrite) << float(idxWrite);