diff --git a/src/Simulator/FloodyFluidSimulator.cpp b/src/Simulator/FloodyFluidSimulator.cpp
index b1ac734d7..03e94e791 100644
--- a/src/Simulator/FloodyFluidSimulator.cpp
+++ b/src/Simulator/FloodyFluidSimulator.cpp
@@ -54,14 +54,23 @@ void cFloodyFluidSimulator::SimulateBlock(cChunk * a_Chunk, int a_RelX, int a_Re
 		a_Chunk->GetMeta(a_RelX, a_RelY, a_RelZ)
 	);
 	
-	NIBBLETYPE MyMeta = a_Chunk->GetMeta(a_RelX, a_RelY, a_RelZ);
-	if (!IsAnyFluidBlock(a_Chunk->GetBlock(a_RelX, a_RelY, a_RelZ)))
+	BLOCKTYPE MyBlock; NIBBLETYPE MyMeta;
+	a_Chunk->GetBlockTypeMeta(a_RelX, a_RelY, a_RelZ, MyBlock, MyMeta);
+
+	if (!IsAnyFluidBlock(MyBlock))
 	{
 		// Can happen - if a block is scheduled for simulating and gets replaced in the meantime.
 		FLOG("  BadBlockType exit");
 		return;
 	}
 
+	// When in contact with water, lava should harden
+	if (HardenBlock(a_Chunk, a_RelX, a_RelY, a_RelZ, MyBlock, MyMeta))
+	{
+		// Block was changed, bail out
+		return;
+	}
+
 	if (MyMeta != 0)
 	{
 		// Source blocks aren't checked for tributaries, others are.
@@ -309,6 +318,8 @@ void cFloodyFluidSimulator::SpreadToNeighbor(cChunk * a_NearChunk, int a_RelX, i
 		a_NewMeta
 	);
 	a_NearChunk->UnboundedRelSetBlock(a_RelX, a_RelY, a_RelZ, m_FluidBlock, a_NewMeta);
+
+	HardenBlock(a_NearChunk, a_RelX, a_RelY, a_RelZ, m_FluidBlock, a_NewMeta);
 }
 
 
@@ -361,3 +372,56 @@ bool cFloodyFluidSimulator::CheckNeighborsForSource(cChunk * a_Chunk, int a_RelX
 
 
 
+
+bool cFloodyFluidSimulator::HardenBlock(cChunk * a_Chunk, int a_RelX, int a_RelY, int a_RelZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_Meta)
+{
+	// Only lava blocks can harden
+	if (!IsBlockLava(a_BlockType))
+	{
+		return false;
+	}
+
+	bool ShouldHarden = false;
+
+	BLOCKTYPE BlockType;
+	NIBBLETYPE BlockMeta;
+	static const Vector3i Coords[] =
+	{
+		Vector3i( 1, 0,  0),
+		Vector3i(-1, 0,  0),
+		Vector3i( 0, 0,  1),
+		Vector3i( 0, 0, -1),
+	};
+	for (size_t i = 0; i < ARRAYCOUNT(Coords); i++)
+	{
+		if (!a_Chunk->UnboundedRelGetBlock(a_RelX + Coords[i].x, a_RelY, a_RelZ + Coords[i].z, BlockType, BlockMeta))
+		{
+			continue;
+		}
+		if (IsBlockWater(BlockType))
+		{
+			ShouldHarden = true;
+		}
+	}  // for i - Coords[]
+
+	if (ShouldHarden)
+	{
+		if (a_Meta == 0)
+		{
+			// Source lava block
+			a_Chunk->UnboundedRelSetBlock(a_RelX, a_RelY, a_RelZ, E_BLOCK_OBSIDIAN, 0);
+			return true;
+		}
+		// Ignore last lava level
+		else if (a_Meta <= 4)
+		{
+			a_Chunk->UnboundedRelSetBlock(a_RelX, a_RelY, a_RelZ, E_BLOCK_COBBLESTONE, 0);
+			return true;
+		}
+	}
+
+	return false;
+}
+
+
+
diff --git a/src/Simulator/FloodyFluidSimulator.h b/src/Simulator/FloodyFluidSimulator.h
index 5fd91b2b1..632de3bb2 100644
--- a/src/Simulator/FloodyFluidSimulator.h
+++ b/src/Simulator/FloodyFluidSimulator.h
@@ -47,6 +47,12 @@ protected:
 	/** Checks if there are enough neighbors to create a source at the coords specified; turns into source and returns true if so. */
 	bool CheckNeighborsForSource(cChunk * a_Chunk, int a_RelX, int a_RelY, int a_RelZ);
 
+	/** Checks if the specified block should harden (Water/Lava interaction) and if so, converts it to a suitable block.
+	 *
+	 * Returns whether the block was changed or not.
+	 */
+	bool HardenBlock(cChunk * a_Chunk, int a_RelX, int a_RelY, int a_RelZ, BLOCKTYPE a_BlockType, NIBBLETYPE a_Meta);
+
 	/** Spread water to neighbors.
 	 *
 	 * May be overridden to provide more sophisticated algorithms.
diff --git a/src/Simulator/VanillaFluidSimulator.cpp b/src/Simulator/VanillaFluidSimulator.cpp
index 5308d162b..78aff9d68 100644
--- a/src/Simulator/VanillaFluidSimulator.cpp
+++ b/src/Simulator/VanillaFluidSimulator.cpp
@@ -86,7 +86,7 @@ int cVanillaFluidSimulator::CalculateFlowCost(cChunk * a_Chunk, int a_RelX, int
 	{
 		return Cost;
 	}
-	if (!IsPassableForFluid(BlockType))
+	if (!IsPassableForFluid(BlockType) && !IsBlockLiquid(BlockType))
 	{
 		return Cost;
 	}
@@ -96,7 +96,7 @@ int cVanillaFluidSimulator::CalculateFlowCost(cChunk * a_Chunk, int a_RelX, int
 	{
 		return Cost;
 	}
-	if (IsPassableForFluid(BlockType))
+	if (IsPassableForFluid(BlockType) || IsBlockLiquid(BlockType))
 	{
 		// Path found, exit
 		return a_Iteration;