diff --git a/source/blocks/BlockDirt.h b/source/blocks/BlockDirt.h
index 2edfa5608..f6ba1c887 100644
--- a/source/blocks/BlockDirt.h
+++ b/source/blocks/BlockDirt.h
@@ -25,41 +25,43 @@ public:
 	
 	void OnUpdate(cWorld *a_World, int a_X, int a_Y, int a_Z) override
 	{
-		if(m_BlockID == E_BLOCK_GRASS)
+		if (m_BlockID != E_BLOCK_GRASS)
 		{
-			//Grass becomes dirt if there is something on top of them
-			BLOCKTYPE Above = a_World->GetBlock(a_X, a_Y + 1, a_Z);
-			if(!g_BlockTransparent[Above] && !g_BlockOneHitDig[Above])
+			return;
+		}
+		
+		// Grass becomes dirt if there is something on top of it:
+		BLOCKTYPE Above = a_World->GetBlock(a_X, a_Y + 1, a_Z);
+		if (!g_BlockTransparent[Above] && !g_BlockOneHitDig[Above])
+		{
+			a_World->FastSetBlock(a_X, a_Y, a_Z, E_BLOCK_DIRT, 0);
+			return;
+		}
+		
+		// Grass spreads to adjacent blocks:
+		MTRand rand;
+		for (int i = 0; i < 2; i++)  // Pick two blocks to grow to
+		{
+			int OfsX = rand.randInt(2) - 1;  // [-1 .. 1]
+			int OfsY = rand.randInt(4) - 3;  // [-3 .. 1]
+			int OfsZ = rand.randInt(2) - 1;  // [-1 .. 1]
+	
+			BLOCKTYPE  DestBlock;
+			NIBBLETYPE DestMeta;
+			a_World->GetBlockTypeMeta(a_X + OfsX, a_Y + OfsY, a_Z + OfsZ, DestBlock, DestMeta);
+			if(DestBlock != E_BLOCK_DIRT)
 			{
-				a_World->FastSetBlock(a_X, a_Y, a_Z, E_BLOCK_DIRT, 0);
+				continue;
 			}
 
-			
-			MTRand rand;
-			for (int i = 0; i < 2; i++)  // Pick two blocks to grow to
+			BLOCKTYPE AboveDest;
+			NIBBLETYPE AboveMeta;
+			a_World->GetBlockTypeMeta(a_X + OfsX, a_Y + OfsY + 1, a_Z + OfsZ, AboveDest, AboveMeta);
+			if (g_BlockOneHitDig[AboveDest] || g_BlockTransparent[AboveDest])
 			{
-				int OfsX = rand.randInt(2) - 1;  // [-1 .. 1]
-				int OfsY = rand.randInt(4) - 3;  // [-3 .. 1]
-				int OfsZ = rand.randInt(2) - 1;  // [-1 .. 1]
-		
-				BLOCKTYPE  DestBlock;
-				NIBBLETYPE DestMeta;
-				a_World->GetBlockTypeMeta(a_X + OfsX, a_Y + OfsY, a_Z + OfsZ, DestBlock, DestMeta);
-				if(DestBlock != E_BLOCK_DIRT)
-				{
-					continue;
-				}
-
-				BLOCKTYPE AboveDest;
-				NIBBLETYPE AboveMeta;
-				a_World->GetBlockTypeMeta(a_X + OfsX, a_Y + OfsY + 1, a_Z + OfsZ, AboveDest, AboveMeta);
-				if (g_BlockOneHitDig[AboveDest] || g_BlockTransparent[AboveDest])
-				{
-					a_World->FastSetBlock(a_X + OfsX, a_Y + OfsY, a_Z + OfsZ, E_BLOCK_GRASS, 0);
-				}
-			}  // for i - repeat twice
-
-		}
+				a_World->FastSetBlock(a_X + OfsX, a_Y + OfsY, a_Z + OfsZ, E_BLOCK_GRASS, 0);
+			}
+		}  // for i - repeat twice
 	}
 	
 };
\ No newline at end of file