diff --git a/src/OpenMesh/Tools/Utils/HeapT.hh b/src/OpenMesh/Tools/Utils/HeapT.hh
index 26365f20..f94b6800 100644
--- a/src/OpenMesh/Tools/Utils/HeapT.hh
+++ b/src/OpenMesh/Tools/Utils/HeapT.hh
@@ -291,11 +291,11 @@ private:
 
   
   /// Get parent's index
-  inline unsigned int parent(unsigned int _i) { return (_i-1)>>1; }
+  inline size_t parent(size_t _i) { return (_i-1)>>1; }
   /// Get left child's index
-  inline unsigned int left(unsigned int _i)   { return (_i<<1)+1; }
+  inline size_t left(size_t _i)   { return (_i<<1)+1; }
   /// Get right child's index
-  inline unsigned int right(unsigned int _i)  { return (_i<<1)+2; }
+  inline size_t right(size_t _i)  { return (_i<<1)+2; }
 
 };
 
diff --git a/src/OpenMesh/Tools/VDPM/VHierarchyWindow.hh b/src/OpenMesh/Tools/VDPM/VHierarchyWindow.hh
index 8125c1f1..7fc3e279 100644
--- a/src/OpenMesh/Tools/VDPM/VHierarchyWindow.hh
+++ b/src/OpenMesh/Tools/VDPM/VHierarchyWindow.hh
@@ -172,7 +172,7 @@ public:
   bool end() { return !(current_pos_ < window_max_-buffer_min_); }
 
   int window_size() const      { return  window_max_ - window_min_; }
-  int buffer_size() const      { return  buffer_max_ - buffer_min_; }
+  size_t buffer_size() const      { return  buffer_max_ - buffer_min_; }
 
   VHierarchyNodeHandle node_handle()
   {