diff --git a/library/PolyVoxCore/include/PolyVoxCore/LargeVolumeSampler.inl b/library/PolyVoxCore/include/PolyVoxCore/LargeVolumeSampler.inl
index 81d5baa9..29bf4644 100644
--- a/library/PolyVoxCore/include/PolyVoxCore/LargeVolumeSampler.inl
+++ b/library/PolyVoxCore/include/PolyVoxCore/LargeVolumeSampler.inl
@@ -103,21 +103,28 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< LargeVolume<VoxelType> >::setPosition(xPos, yPos, zPos);
 
 		// Then we update the voxel pointer
-		const int32_t uXBlock = this->mXPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
-		const int32_t uYBlock = this->mYPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
-		const int32_t uZBlock = this->mZPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
+		if(this->isCurrentPositionValid())
+		{
+			const int32_t uXBlock = this->mXPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
+			const int32_t uYBlock = this->mYPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
+			const int32_t uZBlock = this->mZPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
 
-		const uint16_t uXPosInBlock = static_cast<uint16_t>(this->mXPosInVolume - (uXBlock << this->mVolume->m_uBlockSideLengthPower));
-		const uint16_t uYPosInBlock = static_cast<uint16_t>(this->mYPosInVolume - (uYBlock << this->mVolume->m_uBlockSideLengthPower));
-		const uint16_t uZPosInBlock = static_cast<uint16_t>(this->mZPosInVolume - (uZBlock << this->mVolume->m_uBlockSideLengthPower));
+			const uint16_t uXPosInBlock = static_cast<uint16_t>(this->mXPosInVolume - (uXBlock << this->mVolume->m_uBlockSideLengthPower));
+			const uint16_t uYPosInBlock = static_cast<uint16_t>(this->mYPosInVolume - (uYBlock << this->mVolume->m_uBlockSideLengthPower));
+			const uint16_t uZPosInBlock = static_cast<uint16_t>(this->mZPosInVolume - (uZBlock << this->mVolume->m_uBlockSideLengthPower));
 
-		const uint32_t uVoxelIndexInBlock = uXPosInBlock + 
-				uYPosInBlock * this->mVolume->m_uBlockSideLength + 
-				uZPosInBlock * this->mVolume->m_uBlockSideLength * this->mVolume->m_uBlockSideLength;
+			const uint32_t uVoxelIndexInBlock = uXPosInBlock + 
+					uYPosInBlock * this->mVolume->m_uBlockSideLength + 
+					uZPosInBlock * this->mVolume->m_uBlockSideLength * this->mVolume->m_uBlockSideLength;
 
-		Block<VoxelType>* pUncompressedCurrentBlock = this->mVolume->getUncompressedBlock(uXBlock, uYBlock, uZBlock);
+			Block<VoxelType>* pUncompressedCurrentBlock = this->mVolume->getUncompressedBlock(uXBlock, uYBlock, uZBlock);
 
-		mCurrentVoxel = pUncompressedCurrentBlock->m_tUncompressedData + uVoxelIndexInBlock;
+			mCurrentVoxel = pUncompressedCurrentBlock->m_tUncompressedData + uVoxelIndexInBlock;
+		}
+		else
+		{
+			mCurrentVoxel = 0;
+		}
 	}
 
 	template <typename VoxelType>
@@ -145,7 +152,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< LargeVolume<VoxelType> >::movePositiveX();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mXPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mXPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			++mCurrentVoxel;			
@@ -164,7 +171,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< LargeVolume<VoxelType> >::movePositiveY();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mYPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mYPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			mCurrentVoxel += this->mVolume->m_uBlockSideLength;
@@ -183,7 +190,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< LargeVolume<VoxelType> >::movePositiveZ();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mZPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mZPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			mCurrentVoxel += this->mVolume->m_uBlockSideLength * this->mVolume->m_uBlockSideLength;
@@ -202,7 +209,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< LargeVolume<VoxelType> >::moveNegativeX();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mXPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mXPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			--mCurrentVoxel;			
@@ -221,7 +228,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< LargeVolume<VoxelType> >::moveNegativeY();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mYPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mYPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			mCurrentVoxel -= this->mVolume->m_uBlockSideLength;
@@ -240,7 +247,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< LargeVolume<VoxelType> >::moveNegativeZ();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mZPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mZPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			mCurrentVoxel -= this->mVolume->m_uBlockSideLength * this->mVolume->m_uBlockSideLength;
diff --git a/library/PolyVoxCore/include/PolyVoxCore/RawVolumeSampler.inl b/library/PolyVoxCore/include/PolyVoxCore/RawVolumeSampler.inl
index 165a1505..ee39efe6 100644
--- a/library/PolyVoxCore/include/PolyVoxCore/RawVolumeSampler.inl
+++ b/library/PolyVoxCore/include/PolyVoxCore/RawVolumeSampler.inl
@@ -68,16 +68,23 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< RawVolume<VoxelType> >::setPosition(xPos, yPos, zPos);
 
 		// Then we update the voxel pointer
-		const Vector3DInt32& v3dLowerCorner = this->mVolume->m_regValidRegion.getLowerCorner();
-		int32_t iLocalXPos = xPos - v3dLowerCorner.getX();
-		int32_t iLocalYPos = yPos - v3dLowerCorner.getY();
-		int32_t iLocalZPos = zPos - v3dLowerCorner.getZ();
+		if(this->isCurrentPositionValid())
+		{
+			const Vector3DInt32& v3dLowerCorner = this->mVolume->m_regValidRegion.getLowerCorner();
+			int32_t iLocalXPos = xPos - v3dLowerCorner.getX();
+			int32_t iLocalYPos = yPos - v3dLowerCorner.getY();
+			int32_t iLocalZPos = zPos - v3dLowerCorner.getZ();
 
-		const int32_t uVoxelIndex = iLocalXPos + 
-				iLocalYPos * this->mVolume->getWidth() + 
-				iLocalZPos * this->mVolume->getWidth() * this->mVolume->getHeight();
+			const int32_t uVoxelIndex = iLocalXPos + 
+					iLocalYPos * this->mVolume->getWidth() + 
+					iLocalZPos * this->mVolume->getWidth() * this->mVolume->getHeight();
 
-		mCurrentVoxel = this->mVolume->m_pData + uVoxelIndex;
+			mCurrentVoxel = this->mVolume->m_pData + uVoxelIndex;
+		}
+		else
+		{
+			mCurrentVoxel = 0;
+		}
 	}
 
 	template <typename VoxelType>
@@ -102,7 +109,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< RawVolume<VoxelType> >::movePositiveX();
 
 		// Then we update the voxel pointer
-		if(this->isCurrentPositionValid())
+		if(this->isCurrentPositionValid() && mCurrentVoxel )
 		{
 			++mCurrentVoxel;
 		}
@@ -119,7 +126,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< RawVolume<VoxelType> >::movePositiveY();
 
 		// Then we update the voxel pointer
-		if(this->isCurrentPositionValid())
+		if(this->isCurrentPositionValid() && mCurrentVoxel )
 		{
 			mCurrentVoxel += this->mVolume->getWidth();
 		}
@@ -136,7 +143,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< RawVolume<VoxelType> >::movePositiveZ();
 
 		// Then we update the voxel pointer
-		if(this->isCurrentPositionValid())
+		if(this->isCurrentPositionValid() && mCurrentVoxel )
 		{
 			mCurrentVoxel += this->mVolume->getWidth() * this->mVolume->getHeight();
 		}
@@ -153,7 +160,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< RawVolume<VoxelType> >::moveNegativeX();
 
 		// Then we update the voxel pointer
-		if(this->isCurrentPositionValid())
+		if(this->isCurrentPositionValid() && mCurrentVoxel )
 		{
 			--mCurrentVoxel;
 		}
@@ -170,7 +177,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< RawVolume<VoxelType> >::moveNegativeY();
 
 		// Then we update the voxel pointer
-		if(this->isCurrentPositionValid())
+		if(this->isCurrentPositionValid() && mCurrentVoxel )
 		{
 			mCurrentVoxel -= this->mVolume->getWidth();
 		}
@@ -187,7 +194,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< RawVolume<VoxelType> >::moveNegativeZ();
 
 		// Then we update the voxel pointer
-		if(this->isCurrentPositionValid())
+		if(this->isCurrentPositionValid() && mCurrentVoxel )
 		{
 			mCurrentVoxel -= this->mVolume->getWidth() * this->mVolume->getHeight();
 		}
diff --git a/library/PolyVoxCore/include/PolyVoxCore/SimpleVolume.inl b/library/PolyVoxCore/include/PolyVoxCore/SimpleVolume.inl
index ae90c549..62b48b4a 100644
--- a/library/PolyVoxCore/include/PolyVoxCore/SimpleVolume.inl
+++ b/library/PolyVoxCore/include/PolyVoxCore/SimpleVolume.inl
@@ -306,6 +306,10 @@ namespace PolyVox
 		uBlockY -= m_regValidRegionInBlocks.getLowerCorner().getY();
 		uBlockZ -= m_regValidRegionInBlocks.getLowerCorner().getZ();
 
+		assert(uBlockX >= 0);
+		assert(uBlockY >= 0);
+		assert(uBlockZ >= 0);
+
 		//Compute the block index
 		uint32_t uBlockIndex =
 				uBlockX + 
diff --git a/library/PolyVoxCore/include/PolyVoxCore/SimpleVolumeSampler.inl b/library/PolyVoxCore/include/PolyVoxCore/SimpleVolumeSampler.inl
index 395f104b..651ef074 100644
--- a/library/PolyVoxCore/include/PolyVoxCore/SimpleVolumeSampler.inl
+++ b/library/PolyVoxCore/include/PolyVoxCore/SimpleVolumeSampler.inl
@@ -117,21 +117,28 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< SimpleVolume<VoxelType> >::setPosition(xPos, yPos, zPos);
 
 		// Then we update the voxel pointer
-		const int32_t uXBlock = this->mXPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
-		const int32_t uYBlock = this->mYPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
-		const int32_t uZBlock = this->mZPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
+		if(this->isCurrentPositionValid())
+		{
+			const int32_t uXBlock = this->mXPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
+			const int32_t uYBlock = this->mYPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
+			const int32_t uZBlock = this->mZPosInVolume >> this->mVolume->m_uBlockSideLengthPower;
 
-		const uint16_t uXPosInBlock = static_cast<uint16_t>(this->mXPosInVolume - (uXBlock << this->mVolume->m_uBlockSideLengthPower));
-		const uint16_t uYPosInBlock = static_cast<uint16_t>(this->mYPosInVolume - (uYBlock << this->mVolume->m_uBlockSideLengthPower));
-		const uint16_t uZPosInBlock = static_cast<uint16_t>(this->mZPosInVolume - (uZBlock << this->mVolume->m_uBlockSideLengthPower));
+			const uint16_t uXPosInBlock = static_cast<uint16_t>(this->mXPosInVolume - (uXBlock << this->mVolume->m_uBlockSideLengthPower));
+			const uint16_t uYPosInBlock = static_cast<uint16_t>(this->mYPosInVolume - (uYBlock << this->mVolume->m_uBlockSideLengthPower));
+			const uint16_t uZPosInBlock = static_cast<uint16_t>(this->mZPosInVolume - (uZBlock << this->mVolume->m_uBlockSideLengthPower));
 
-		const uint32_t uVoxelIndexInBlock = uXPosInBlock + 
-				uYPosInBlock * this->mVolume->m_uBlockSideLength + 
-				uZPosInBlock * this->mVolume->m_uBlockSideLength * this->mVolume->m_uBlockSideLength;
+			const uint32_t uVoxelIndexInBlock = uXPosInBlock + 
+					uYPosInBlock * this->mVolume->m_uBlockSideLength + 
+					uZPosInBlock * this->mVolume->m_uBlockSideLength * this->mVolume->m_uBlockSideLength;
 
-		Block* pUncompressedCurrentBlock = this->mVolume->getUncompressedBlock(uXBlock, uYBlock, uZBlock);
+			Block* pUncompressedCurrentBlock = this->mVolume->getUncompressedBlock(uXBlock, uYBlock, uZBlock);
 
-		mCurrentVoxel = pUncompressedCurrentBlock->m_tUncompressedData + uVoxelIndexInBlock;
+			mCurrentVoxel = pUncompressedCurrentBlock->m_tUncompressedData + uVoxelIndexInBlock;
+		}
+		else
+		{
+			mCurrentVoxel = 0;
+		}
 	}
 	
 	/**
@@ -164,7 +171,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< SimpleVolume<VoxelType> >::movePositiveX();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mXPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mXPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			++mCurrentVoxel;			
@@ -183,7 +190,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< SimpleVolume<VoxelType> >::movePositiveY();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mYPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mYPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			mCurrentVoxel += this->mVolume->m_uBlockSideLength;
@@ -202,7 +209,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< SimpleVolume<VoxelType> >::movePositiveZ();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mZPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mZPosInVolume) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			mCurrentVoxel += this->mVolume->m_uBlockSideLength * this->mVolume->m_uBlockSideLength;
@@ -221,7 +228,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< SimpleVolume<VoxelType> >::moveNegativeX();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mXPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mXPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			--mCurrentVoxel;			
@@ -240,7 +247,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< SimpleVolume<VoxelType> >::moveNegativeY();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mYPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mYPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			mCurrentVoxel -= this->mVolume->m_uBlockSideLength;
@@ -259,7 +266,7 @@ namespace PolyVox
 		BaseVolume<VoxelType>::template Sampler< SimpleVolume<VoxelType> >::moveNegativeZ();
 
 		// Then we update the voxel pointer
-		if((this->isCurrentPositionValid()) && ((this->mZPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
+		if((this->isCurrentPositionValid()) && mCurrentVoxel && ((this->mZPosInVolume + 1) % this->mVolume->m_uBlockSideLength != 0))
 		{
 			//No need to compute new block.
 			mCurrentVoxel -= this->mVolume->m_uBlockSideLength * this->mVolume->m_uBlockSideLength;