diff --git a/.gitmodules b/.gitmodules
index 0439d2ec7..3bbdda328 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -12,3 +12,6 @@
 [submodule "src/pocketmine/lang/locale"]
 	path = src/pocketmine/lang/locale
 	url = https://github.com/pmmp/PocketMine-Language.git
+[submodule "tests/preprocessor"]
+	path = tests/preprocessor
+	url = https://github.com/pmmp/preprocessor.git
diff --git a/src/pocketmine/nbt/tag/ListTag.php b/src/pocketmine/nbt/tag/ListTag.php
index 02aaedf57..43a5be668 100644
--- a/src/pocketmine/nbt/tag/ListTag.php
+++ b/src/pocketmine/nbt/tag/ListTag.php
@@ -203,7 +203,7 @@ class ListTag extends NamedTag implements \ArrayAccess, \Countable{
 				$tags[] = $tag;
 			}
 		}
-		$nbt->putInt(count($tags));
+		$nbt->putInt(count($tags), $network);
 		foreach($tags as $tag){
 			$tag->write($nbt, $network);
 		}
diff --git a/tests/preprocessor b/tests/preprocessor
new file mode 160000
index 000000000..7545b8b44
--- /dev/null
+++ b/tests/preprocessor
@@ -0,0 +1 @@
+Subproject commit 7545b8b444b4bd4cbbb67c804b0a55ac5a0111c9