diff --git a/src/API/BlockAPI.php b/src/API/BlockAPI.php
index 65040a5af..86419be3d 100644
--- a/src/API/BlockAPI.php
+++ b/src/API/BlockAPI.php
@@ -531,19 +531,23 @@ class BlockAPI{
 			return false;
 		}
 
-		if($block->isReplaceable === true and $item->isPlaceable()){
+		if($item->isPlaceable()){
 			$hand = $item->getBlock();
 		}else{
 			return $this->cancelAction($block);
 		}
 		
+		if(!($block->isReplaceable === true or ($hand->getID() === SLAB and $block->getID() === SLAB))){
+			return $this->cancelAction($block);
+		}
+		
 		if($hand->isTransparent === false and $player->entity->inBlock($block->x, $block->y, $block->z)){
 			return $this->cancelAction($block); //Entity in block
 		}
 
 		//$direction = $player->entity->getDirection();
 
-		if($hand->place($this, $item, $player, $block, $target, $data["face"]) === false){
+		if($hand->place($this, $item, $player, $block, $target, $data["face"], $data["fx"], $data["fy"], $data["fz"]) === false){
 			return false;
 		}
 
diff --git a/src/classes/material/Block.php b/src/classes/material/Block.php
index e93df91a3..a6fcdc2c2 100644
--- a/src/classes/material/Block.php
+++ b/src/classes/material/Block.php
@@ -77,7 +77,7 @@ abstract class Block{
 		);
 	}
 	
-	abstract function place(BlockAPI $level, Item $item, Player $player, Block $block, Block $target, $face);
+	abstract function place(BlockAPI $level, Item $item, Player $player, Block $block, Block $target, $face, $fx, $fy, $fz);
 	
 	abstract function onActivate(BlockAPI $level, Item $item, Player $player);
 	
diff --git a/src/classes/material/block/GenericBlock.php b/src/classes/material/block/GenericBlock.php
index bddb14430..4bf14cae7 100644
--- a/src/classes/material/block/GenericBlock.php
+++ b/src/classes/material/block/GenericBlock.php
@@ -30,7 +30,7 @@ class GenericBlock extends Block{
 	public function __construct($id, $meta = 0, $name = "Unknown"){
 		parent::__construct($id, $meta, $name);
 	}	
-	public function place(BlockAPI $level, Item $item, Player $player, Block $block, Block $target, $face){
+	public function place(BlockAPI $level, Item $item, Player $player, Block $block, Block $target, $face, $fx, $fy, $fz){
 		if($block->inWorld === true){
 			$level->setBlock($block, $this->id, $this->getMetadata());
 			return true;
diff --git a/src/classes/material/block/plant/Sapling.php b/src/classes/material/block/plant/Sapling.php
index 61f5d6aab..5b69ac993 100644
--- a/src/classes/material/block/plant/Sapling.php
+++ b/src/classes/material/block/plant/Sapling.php
@@ -43,7 +43,7 @@ class SaplingBlock extends TransparentBlock{
 		$this->name = $names[$this->meta & 0x03];
 	}
 	
-	public function place(BlockAPI $level, Item $item, Player $player, Block $block, Block $target, $face){
+	public function place(BlockAPI $level, Item $item, Player $player, Block $block, Block $target, $face, $fx, $fy, $fz){
 		if($block->inWorld === true){
 			$down = $level->getBlockFace($block, 0);
 			if($down->getID() === 2 or $down->getID() === 3 or $down->getID() === 60){
diff --git a/src/classes/material/block/solid/Slab.php b/src/classes/material/block/solid/Slab.php
index db5519da3..1b62526cd 100644
--- a/src/classes/material/block/solid/Slab.php
+++ b/src/classes/material/block/solid/Slab.php
@@ -41,4 +41,38 @@ class SlabBlock extends TransparentBlock{
 		$this->name = (($this->meta & 0x08) === 0x08 ? "Upper ":"") . $names[$this->meta & 0x07] . " Slab";
 	}
 	
+	public function place(BlockAPI $level, Item $item, Player $player, Block $block, Block $target, $face, $fx, $fy, $fz){
+		if($block->inWorld === true){
+			$this->meta = $this->meta & 0x07;
+			if($face === 0){
+				if($target->getID() === SLAB and ($target->getMetadata() & 0x08) === 0x08 and ($target->getMetadata() & 0x07) === ($this->meta & 0x07)){
+					$level->setBlock($target, DOUBLE_SLAB, $this->meta & 0x07);
+					return true;
+				}else{
+					$this->meta |= 0x08;
+				}
+			}elseif($face === 1){
+				if($target->getID() === SLAB and ($target->getMetadata() & 0x08) === 0 and ($target->getMetadata() & 0x07) === ($this->meta & 0x07)){
+					$level->setBlock($target, DOUBLE_SLAB, $this->meta & 0x07);
+					return true;
+				}
+			}else{
+				if($block->getID() === SLAB){
+					if(($block->getMetadata() & 0x07) === ($this->meta & 0x07)){
+						$level->setBlock($block, DOUBLE_SLAB, $this->meta & 0x07);
+						return true;
+					}
+					return false;
+				}else{
+					if($fy > 0.5){
+						$this->meta |= 0x08;
+					}
+				}
+			}			
+			$level->setBlock($block, $this->id, $this->meta);
+			return true;
+		}
+		return false;
+	}
+	
 }
\ No newline at end of file