diff --git a/voxel_buffer.h b/voxel_buffer.h
index b428c2e..0a192be 100644
--- a/voxel_buffer.h
+++ b/voxel_buffer.h
@@ -83,7 +83,7 @@ public:
 	void copy_from(const VoxelBuffer &other, Vector3i src_min, Vector3i src_max, Vector3i dst_min, unsigned int channel_index = 0);
 
 	_FORCE_INLINE_ bool validate_pos(unsigned int x, unsigned int y, unsigned int z) const {
-		return x < _size.x && y < _size.y && z < _size.x;
+		return x < _size.x && y < _size.y && z < _size.z;
 	}
 
 	_FORCE_INLINE_ unsigned int index(unsigned int x, unsigned int y, unsigned int z) const {