diff --git a/Code/Mantid/Vates/VatesAPI/src/vtkMDLineFactory.cpp b/Code/Mantid/Vates/VatesAPI/src/vtkMDLineFactory.cpp
index 6864152a1824..071d6aaa09c0 100644
--- a/Code/Mantid/Vates/VatesAPI/src/vtkMDLineFactory.cpp
+++ b/Code/Mantid/Vates/VatesAPI/src/vtkMDLineFactory.cpp
@@ -97,7 +97,8 @@ namespace Mantid
         double progressFactor = 0.5/double(it->getDataSize());
         double progressOffset = 0.5;
 
-        for(size_t iBox = 0; iBox < it->getDataSize(); ++iBox)
+        size_t iBox = 0;
+        do
         {
           progressUpdating.eventRaised(double(iBox)*progressFactor);
 
@@ -133,8 +134,8 @@ namespace Mantid
           {
             useBox[iBox] = false;
           }
-          it->next();
-        }
+          ++iBox;
+        } while (it->next());
 
         delete[] masks;
         for(size_t ii = 0; ii < it->getDataSize() ; ++ii)
diff --git a/Code/Mantid/Vates/VatesAPI/src/vtkMDQuadFactory.cpp b/Code/Mantid/Vates/VatesAPI/src/vtkMDQuadFactory.cpp
index e1721843b398..a5d24df5f1d3 100644
--- a/Code/Mantid/Vates/VatesAPI/src/vtkMDQuadFactory.cpp
+++ b/Code/Mantid/Vates/VatesAPI/src/vtkMDQuadFactory.cpp
@@ -93,7 +93,8 @@ namespace Mantid
         double progressFactor = 0.5/double(it->getDataSize());
         double progressOffset = 0.5;
 
-        for(size_t iBox = 0; iBox < it->getDataSize(); ++iBox)
+        size_t iBox = 0;
+        do
         {
           progressUpdating.eventRaised(progressFactor * double(iBox));
 
@@ -129,8 +130,8 @@ namespace Mantid
           {
             useBox[iBox] = false;
           }
-          it->next();
-        }
+          ++iBox;
+        } while (it->next());
 
         delete[] masks;
         for(size_t ii = 0; ii < it->getDataSize() ; ++ii)