diff --git a/source/Simulator/Simulator.cpp b/source/Simulator/Simulator.cpp
index 78e12324a..06fd0f858 100644
--- a/source/Simulator/Simulator.cpp
+++ b/source/Simulator/Simulator.cpp
@@ -32,12 +32,18 @@ cSimulator::~cSimulator()
 void cSimulator::WakeUp(int a_BlockX, int a_BlockY, int a_BlockZ, cChunk * a_Chunk)
 {
 	AddBlock(a_BlockX,     a_BlockY,     a_BlockZ,     a_Chunk);
-	AddBlock(a_BlockX,     a_BlockY - 1, a_BlockZ,     a_Chunk);
-	AddBlock(a_BlockX,     a_BlockY + 1, a_BlockZ,     a_Chunk);
 	AddBlock(a_BlockX - 1, a_BlockY,     a_BlockZ,     a_Chunk->GetNeighborChunk(a_BlockX - 1, a_BlockZ));
 	AddBlock(a_BlockX + 1, a_BlockY,     a_BlockZ,     a_Chunk->GetNeighborChunk(a_BlockX + 1, a_BlockZ));
 	AddBlock(a_BlockX,     a_BlockY,     a_BlockZ - 1, a_Chunk->GetNeighborChunk(a_BlockX,     a_BlockZ - 1));
 	AddBlock(a_BlockX,     a_BlockY,     a_BlockZ + 1, a_Chunk->GetNeighborChunk(a_BlockX,     a_BlockZ + 1));
+	if (a_BlockY > 0)
+	{
+		AddBlock(a_BlockX,   a_BlockY - 1, a_BlockZ,     a_Chunk);
+	}
+	if (a_BlockY < cChunkDef::Height - 1)
+	{
+		AddBlock(a_BlockX,   a_BlockY + 1, a_BlockZ,     a_Chunk);
+	}
 }