diff --git a/Engine/lib/opcode/OPC_AABBTree.cpp b/Engine/lib/opcode/OPC_AABBTree.cpp
index 0ad32a6e1..7da56c2f7 100644
--- a/Engine/lib/opcode/OPC_AABBTree.cpp
+++ b/Engine/lib/opcode/OPC_AABBTree.cpp
@@ -291,21 +291,21 @@ bool AABBTreeNode::Subdivide(AABBTreeBuilder* builder)
 		// Set last bit to tell it shouldn't be freed ### pretty ugly, find a better way. Maybe one bit in mNbPrimitives
 		ASSERT(!(udword(&Pool[Count+0])&1));
 		ASSERT(!(udword(&Pool[Count+1])&1));
-		mPos = udword(&Pool[Count+0])|1;
+		mPos = size_t(&Pool[Count+0])|1;
 #ifndef OPC_NO_NEG_VANILLA_TREE
-		mNeg = udword(&Pool[Count+1])|1;
+		mNeg = size_t(&Pool[Count+1])|1;
 #endif
 	}
 	else
 	{
 		// Non-complete trees and/or Opcode 1.2 allocate nodes on-the-fly
 #ifndef OPC_NO_NEG_VANILLA_TREE
-		mPos = (udword)new AABBTreeNode;	CHECKALLOC(mPos);
-		mNeg = (udword)new AABBTreeNode;	CHECKALLOC(mNeg);
+		mPos = (size_t)new AABBTreeNode;	CHECKALLOC(mPos);
+		mNeg = (size_t)new AABBTreeNode;	CHECKALLOC(mNeg);
 #else
 		AABBTreeNode* PosNeg = new AABBTreeNode[2];
 		CHECKALLOC(PosNeg);
-		mPos = (udword)PosNeg;
+		mPos = (size_t)PosNeg;
 #endif
 	}
 
diff --git a/Engine/lib/opcode/OPC_AABBTree.h b/Engine/lib/opcode/OPC_AABBTree.h
index 298f4827a..ee2533db6 100644
--- a/Engine/lib/opcode/OPC_AABBTree.h
+++ b/Engine/lib/opcode/OPC_AABBTree.h
@@ -43,7 +43,7 @@
 		/* Following data always belong to the BV-tree, regardless of what the tree actually contains.*/				\
 		/* Whatever happens we need the two children and the enclosing volume.*/										\
 				volume				mBV;		/* Global bounding-volume enclosing all the node-related primitives */	\
-				udword				mPos;		/* "Positive" & "Negative" children */
+				size_t				mPos;		/* "Positive" & "Negative" children */
 #else
 	//! TO BE DOCUMENTED
 	#define IMPLEMENT_TREE(base_class, volume)																			\
@@ -68,8 +68,8 @@
 		/* Following data always belong to the BV-tree, regardless of what the tree actually contains.*/				\
 		/* Whatever happens we need the two children and the enclosing volume.*/										\
 				volume				mBV;		/* Global bounding-volume enclosing all the node-related primitives */	\
-				udword				mPos;		/* "Positive" child */													\
-				udword				mNeg;		/* "Negative" child */
+				size_t				mPos;		/* "Positive" child */													\
+				size_t				mNeg;		/* "Negative" child */
 #endif
 
 	typedef		void				(*CullingCallback)		(udword nb_primitives, udword* node_primitives, BOOL need_clipping, void* user_data);
diff --git a/Engine/lib/opcode/OPC_OptimizedTree.cpp b/Engine/lib/opcode/OPC_OptimizedTree.cpp
index 81b3a2462..0779795c4 100644
--- a/Engine/lib/opcode/OPC_OptimizedTree.cpp
+++ b/Engine/lib/opcode/OPC_OptimizedTree.cpp
@@ -118,7 +118,7 @@ static void _BuildCollisionTree(AABBCollisionNode* linear, const udword box_id,
 		udword PosID = current_id++;	// Get a new id for positive child
 		udword NegID = current_id++;	// Get a new id for negative child
 		// Setup box data as the forthcoming new P pointer
-		linear[box_id].mData = (udword)&linear[PosID];
+		linear[box_id].mData = (size_t)&linear[PosID];
 		// Make sure it's not marked as leaf
 		ASSERT(!(linear[box_id].mData&1));
 		// Recurse with new IDs
@@ -171,7 +171,7 @@ static void _BuildNoLeafTree(AABBNoLeafNode* linear, const udword box_id, udword
 		// Get a new id for positive child
 		udword PosID = current_id++;
 		// Setup box data
-		linear[box_id].mPosData = (udword)&linear[PosID];
+		linear[box_id].mPosData = (size_t)&linear[PosID];
 		// Make sure it's not marked as leaf
 		ASSERT(!(linear[box_id].mPosData&1));
 		// Recurse
@@ -192,7 +192,7 @@ static void _BuildNoLeafTree(AABBNoLeafNode* linear, const udword box_id, udword
 		// Get a new id for negative child
 		udword NegID = current_id++;
 		// Setup box data
-		linear[box_id].mNegData = (udword)&linear[NegID];
+		linear[box_id].mNegData = (size_t)&linear[NegID];
 		// Make sure it's not marked as leaf
 		ASSERT(!(linear[box_id].mNegData&1));
 		// Recurse
@@ -549,8 +549,8 @@ bool AABBNoLeafTree::Walk(GenericWalkingCallback callback, void* user_data) cons
 	if(!(Data&1))													\
 	{																\
 		/* Compute box number */									\
-		udword Nb = (Data - udword(Nodes))/Nodes[i].GetNodeSize();	\
-		Data = udword(&mNodes[Nb]);									\
+		udword Nb = (Data - size_t(Nodes))/Nodes[i].GetNodeSize();	\
+		Data = (size_t) &mNodes[Nb]		;									\
 	}																\
 	/* ...remapped */												\
 	mNodes[i].member = Data;
@@ -612,7 +612,7 @@ bool AABBQuantizedTree::Build(AABBTree* tree)
 		INIT_QUANTIZATION
 
 		// Quantize
-		udword Data;
+		size_t Data;
 		for(udword i=0;i<mNbNodes;i++)
 		{
 			PERFORM_QUANTIZATION
@@ -727,7 +727,7 @@ bool AABBQuantizedNoLeafTree::Build(AABBTree* tree)
 		INIT_QUANTIZATION
 
 		// Quantize
-		udword Data;
+		size_t Data;
 		for(udword i=0;i<mNbNodes;i++)
 		{
 			PERFORM_QUANTIZATION
diff --git a/Engine/lib/opcode/OPC_OptimizedTree.h b/Engine/lib/opcode/OPC_OptimizedTree.h
index 78fc4ef37..23f972d94 100644
--- a/Engine/lib/opcode/OPC_OptimizedTree.h
+++ b/Engine/lib/opcode/OPC_OptimizedTree.h
@@ -36,7 +36,7 @@
 		inline_			udword				GetNodeSize()	const	{ return SIZEOFOBJECT;				}	\
 																											\
 						volume				mAABB;															\
-						udword				mData;
+						size_t				mData;
 
 	//! Common interface for a node of a no-leaf tree
 	#define IMPLEMENT_NOLEAF_NODE(base_class, volume)														\
@@ -56,8 +56,8 @@
 		inline_			udword				GetNodeSize()		const	{ return SIZEOFOBJECT;			}	\
 																											\
 						volume				mAABB;															\
-						udword				mPosData;														\
-						udword				mNegData;
+						size_t				mPosData;														\
+						size_t				mNegData;
 
 	class OPCODE_API AABBCollisionNode
 	{