diff --git a/src/pocketmine/network/mcpe/protocol/ClientboundMapItemDataPacket.php b/src/pocketmine/network/mcpe/protocol/ClientboundMapItemDataPacket.php
index 2df98c735..64321432d 100644
--- a/src/pocketmine/network/mcpe/protocol/ClientboundMapItemDataPacket.php
+++ b/src/pocketmine/network/mcpe/protocol/ClientboundMapItemDataPacket.php
@@ -114,7 +114,9 @@ class ClientboundMapItemDataPacket extends DataPacket{
 			$this->yOffset = $this->getVarInt();
 
 			$count = $this->getUnsignedVarInt();
-			assert($count === $this->width * $this->height);
+			if($count !== $this->width * $this->height){
+				throw new \UnexpectedValueException("Expected colour count of " . ($this->height * $this->width) . " (height $this->height * width $this->width), got $count");
+			}
 
 			for($y = 0; $y < $this->height; ++$y){
 				for($x = 0; $x < $this->width; ++$x){
diff --git a/src/pocketmine/network/mcpe/protocol/DataPacket.php b/src/pocketmine/network/mcpe/protocol/DataPacket.php
index a3141c535..44bafbaad 100644
--- a/src/pocketmine/network/mcpe/protocol/DataPacket.php
+++ b/src/pocketmine/network/mcpe/protocol/DataPacket.php
@@ -76,7 +76,9 @@ abstract class DataPacket extends NetworkBinaryStream{
 
 	protected function decodeHeader(){
 		$pid = $this->getUnsignedVarInt();
-		assert($pid === static::NETWORK_ID);
+		if($pid !== static::NETWORK_ID){
+			throw new \UnexpectedValueException("Expected " . static::NETWORK_ID . " for packet ID, got $pid");
+		}
 	}
 
 	/**