diff --git a/src/pocketmine/block/Air.php b/src/pocketmine/block/Air.php
index 4ade171fc..1e8e84d6c 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(Block $with = null) : bool{
+	public function canBeReplaced() : bool{
 		return true;
 	}
 
diff --git a/src/pocketmine/block/Block.php b/src/pocketmine/block/Block.php
index 48facec70..dd5148780 100644
--- a/src/pocketmine/block/Block.php
+++ b/src/pocketmine/block/Block.php
@@ -284,11 +284,9 @@ class Block extends Position implements BlockIds, Metadatable{
 	}
 
 	/**
-	 * @param Block|null $with
-	 *
 	 * @return bool
 	 */
-	public function canBeReplaced(Block $with = null) : bool{
+	public function canBeReplaced() : bool{
 		return false;
 	}
 
diff --git a/src/pocketmine/block/DoublePlant.php b/src/pocketmine/block/DoublePlant.php
index 5637fda4c..ac76e6db9 100644
--- a/src/pocketmine/block/DoublePlant.php
+++ b/src/pocketmine/block/DoublePlant.php
@@ -38,7 +38,7 @@ class DoublePlant extends Flowable{
 		$this->meta = $meta;
 	}
 
-	public function canBeReplaced(Block $with = null) : bool{
+	public function canBeReplaced() : 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 0b44d54bc..edeeb56bb 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(Block $with = null) : bool{
+	public function canBeReplaced() : bool{
 		return true;
 	}
 
diff --git a/src/pocketmine/block/Liquid.php b/src/pocketmine/block/Liquid.php
index ad639cdf6..185f271e4 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(Block $with = null) : bool{
+	public function canBeReplaced() : bool{
 		return true;
 	}
 
diff --git a/src/pocketmine/block/SnowLayer.php b/src/pocketmine/block/SnowLayer.php
index 8b602161d..a9163f8af 100644
--- a/src/pocketmine/block/SnowLayer.php
+++ b/src/pocketmine/block/SnowLayer.php
@@ -42,7 +42,7 @@ class SnowLayer extends Flowable{
 		return "Snow Layer";
 	}
 
-	public function canBeReplaced(Block $with = null) : bool{
+	public function canBeReplaced() : bool{
 		return true;
 	}
 
diff --git a/src/pocketmine/block/TallGrass.php b/src/pocketmine/block/TallGrass.php
index d9836d395..54337f3de 100644
--- a/src/pocketmine/block/TallGrass.php
+++ b/src/pocketmine/block/TallGrass.php
@@ -37,7 +37,7 @@ class TallGrass extends Flowable{
 		$this->meta = $meta;
 	}
 
-	public function canBeReplaced(Block $with = null) : bool{
+	public function canBeReplaced() : bool{
 		return true;
 	}
 
diff --git a/src/pocketmine/block/WoodenSlab.php b/src/pocketmine/block/WoodenSlab.php
index 1fa697d6b..0688554e7 100644
--- a/src/pocketmine/block/WoodenSlab.php
+++ b/src/pocketmine/block/WoodenSlab.php
@@ -78,10 +78,6 @@ 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 $blockReplace, Block $blockClicked, 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 4132224af..d9134f652 100644
--- a/src/pocketmine/level/Level.php
+++ b/src/pocketmine/level/Level.php
@@ -1723,20 +1723,23 @@ class Level implements ChunkManager, Metadatable{
 			return true;
 		}
 
-		if(!$item->canBePlaced()){
+		if($item->canBePlaced()){
+			$hand = $item->getBlock();
+			$hand->position($blockReplace);
+		}else{
 			return false;
 		}
 
-		$hand = $item->getBlock();
+		if(!($blockReplace->canBeReplaced() === true or ($hand->getId() === Item::WOODEN_SLAB and $blockReplace->getId() === Item::WOODEN_SLAB) or ($hand->getId() === Item::STONE_SLAB and $blockReplace->getId() === Item::STONE_SLAB))){
+			return false;
+		}
 
-		if($blockClicked->canBeReplaced($hand)){
+		if($blockClicked->canBeReplaced() === true){
 			$blockReplace = $blockClicked;
-		}elseif(!$blockReplace->canBeReplaced($hand)){
-			return false;
+			$hand->position($blockReplace);
+			//$face = -1;
 		}
 
-		$hand->position($blockReplace);
-
 		if($hand->isSolid() === true and $hand->getBoundingBox() !== null){
 			$entities = $this->getCollidingEntities($hand->getBoundingBox());
 			foreach($entities as $e){