diff --git a/src/pocketmine/block/Air.php b/src/pocketmine/block/Air.php
index e8f519a96..a58ad31a3 100644
--- a/src/pocketmine/block/Air.php
+++ b/src/pocketmine/block/Air.php
@@ -54,7 +54,7 @@ class Air extends Transparent{
 		return true;
 	}
 
-	public function canBeReplaced() : bool{
+	public function canBeReplaced(Block $with = null) : bool{
 		return true;
 	}
 
diff --git a/src/pocketmine/block/Block.php b/src/pocketmine/block/Block.php
index 5970a865e..526099b2e 100644
--- a/src/pocketmine/block/Block.php
+++ b/src/pocketmine/block/Block.php
@@ -597,9 +597,11 @@ class Block extends Position implements BlockIds, Metadatable{
 	}
 
 	/**
+	 * @param Block|null $with
+	 *
 	 * @return bool
 	 */
-	public function canBeReplaced() : bool{
+	public function canBeReplaced(Block $with = null) : bool{
 		return false;
 	}
 
diff --git a/src/pocketmine/block/DoublePlant.php b/src/pocketmine/block/DoublePlant.php
index 386dcf4c0..0d820a2a0 100644
--- a/src/pocketmine/block/DoublePlant.php
+++ b/src/pocketmine/block/DoublePlant.php
@@ -37,7 +37,7 @@ class DoublePlant extends Flowable{
 		$this->meta = $meta;
 	}
 
-	public function canBeReplaced() : bool{
+	public function canBeReplaced(Block $with = null) : bool{
 		return $this->meta === 2 or $this->meta === 3; //grass or fern
 	}
 
diff --git a/src/pocketmine/block/Fire.php b/src/pocketmine/block/Fire.php
index e0825d65a..8e4878339 100644
--- a/src/pocketmine/block/Fire.php
+++ b/src/pocketmine/block/Fire.php
@@ -57,7 +57,7 @@ class Fire extends Flowable{
 		return false;
 	}
 
-	public function canBeReplaced() : bool{
+	public function canBeReplaced(Block $with = null) : bool{
 		return true;
 	}
 
diff --git a/src/pocketmine/block/Liquid.php b/src/pocketmine/block/Liquid.php
index 254196938..1178e3a62 100644
--- a/src/pocketmine/block/Liquid.php
+++ b/src/pocketmine/block/Liquid.php
@@ -41,7 +41,7 @@ abstract class Liquid extends Transparent{
 		return false;
 	}
 
-	public function canBeReplaced() : bool{
+	public function canBeReplaced(Block $with = null) : bool{
 		return true;
 	}
 
diff --git a/src/pocketmine/block/SnowLayer.php b/src/pocketmine/block/SnowLayer.php
index 12d617eb4..eca0c9492 100644
--- a/src/pocketmine/block/SnowLayer.php
+++ b/src/pocketmine/block/SnowLayer.php
@@ -41,7 +41,7 @@ class SnowLayer extends Flowable{
 		return "Snow Layer";
 	}
 
-	public function canBeReplaced() : bool{
+	public function canBeReplaced(Block $with = null) : bool{
 		return true;
 	}
 
diff --git a/src/pocketmine/block/TallGrass.php b/src/pocketmine/block/TallGrass.php
index 73723aa25..eb8d93d55 100644
--- a/src/pocketmine/block/TallGrass.php
+++ b/src/pocketmine/block/TallGrass.php
@@ -36,7 +36,7 @@ class TallGrass extends Flowable{
 		$this->meta = $meta;
 	}
 
-	public function canBeReplaced() : bool{
+	public function canBeReplaced(Block $with = null) : bool{
 		return true;
 	}
 
diff --git a/src/pocketmine/block/WoodenSlab.php b/src/pocketmine/block/WoodenSlab.php
index 320640944..7310145a0 100644
--- a/src/pocketmine/block/WoodenSlab.php
+++ b/src/pocketmine/block/WoodenSlab.php
@@ -78,6 +78,10 @@ class WoodenSlab extends Transparent{
 		}
 	}
 
+	public function canBeReplaced(Block $with = null) : bool{
+		return $with !== null and $with->getId() === $this->getId() and ($with->getDamage() & 0x07) === ($this->getDamage() & 0x07);
+	}
+
 	public function place(Item $item, Block $block, Block $target, int $face, Vector3 $facePos, Player $player = null) : bool{
 		$this->meta &= 0x07;
 		if($face === Vector3::SIDE_DOWN){
diff --git a/src/pocketmine/level/Level.php b/src/pocketmine/level/Level.php
index 60f4dee34..b6ac770ae 100644
--- a/src/pocketmine/level/Level.php
+++ b/src/pocketmine/level/Level.php
@@ -1777,23 +1777,20 @@ class Level implements ChunkManager, Metadatable{
 			return true;
 		}
 
-		if($item->canBePlaced()){
-			$hand = $item->getBlock();
-			$hand->position($block);
-		}else{
+		if(!$item->canBePlaced()){
 			return false;
 		}
 
-		if(!($block->canBeReplaced() === true or ($hand->getId() === Item::WOODEN_SLAB and $block->getId() === Item::WOODEN_SLAB) or ($hand->getId() === Item::STONE_SLAB and $block->getId() === Item::STONE_SLAB))){
-			return false;
-		}
+		$hand = $item->getBlock();
 
-		if($target->canBeReplaced() === true){
+		if($target->canBeReplaced($hand)){
 			$block = $target;
-			$hand->position($block);
-			//$face = -1;
+		}elseif(!$block->canBeReplaced($hand)){
+			return false;
 		}
 
+		$hand->position($block);
+
 		if($hand->isSolid() === true and $hand->getBoundingBox() !== null){
 			$entities = $this->getCollidingEntities($hand->getBoundingBox());
 			$realCount = 0;
@@ -1834,7 +1831,7 @@ class Level implements ChunkManager, Metadatable{
 			}
 		}
 
-		if($hand->place($item, $block, $target, $face, $facePos, $player) === false){
+		if(!$hand->place($item, $block, $target, $face, $facePos, $player)){
 			return false;
 		}