diff --git a/Src/Containers/FOctree.hpp b/Src/Containers/FOctree.hpp
index ca3a9278b630a8bc94d1090e5ae9870efdcf3bcb..a700afae5b1f0c8131c00ea328ede69f53d8278a 100755
--- a/Src/Containers/FOctree.hpp
+++ b/Src/Containers/FOctree.hpp
@@ -94,8 +94,10 @@ class FOctree : public FNoCopyable {
      * @return the box num at the leaf level that contains inRelativePosition
      */
     int getTreeCoordinate(const FReal inRelativePosition) const {
-        FAssertLF( (inRelativePosition >= 0 && inRelativePosition < this->boxWidth), "inRelativePosition : ",inRelativePosition );
-        FAssertLF( inRelativePosition >= 0 && inRelativePosition < this->boxWidth, "Particle out of box" );
+        FAssertLF( (inRelativePosition >= 0 && inRelativePosition <= this->boxWidth), "inRelativePosition : ",inRelativePosition );
+        if(inRelativePosition == this->boxWidth){
+            return FMath::pow2(height-1)-1;
+        }
         const FReal indexFReal = inRelativePosition / this->boxWidthAtLevel[this->leafIndex];
         return static_cast<int>(indexFReal);
     }