diff --git a/src/pocketmine/block/BlockFactory.php b/src/pocketmine/block/BlockFactory.php
index cafa297db..7aadc7839 100644
--- a/src/pocketmine/block/BlockFactory.php
+++ b/src/pocketmine/block/BlockFactory.php
@@ -59,6 +59,9 @@ class BlockFactory{
 	/** @var int[] */
 	public static $legacyIdMap = [];
 
+	/** @var int */
+	private static $lastRuntimeId = 0;
+
 	/**
 	 * Initializes the block factory. By default this is called only once on server start, however you may wish to use
 	 * this if you need to reset the block factory back to its original defaults for whatever reason.
@@ -336,12 +339,11 @@ class BlockFactory{
 			}
 		}
 
+		/** @var mixed[] $runtimeIdMap */
 		$runtimeIdMap = json_decode(file_get_contents(\pocketmine\RESOURCE_PATH . "runtimeid_table.json"), true);
 		foreach($runtimeIdMap as $obj){
-			self::$staticRuntimeIdMap[$obj["id"] << 4 | $obj["data"]] = $obj["runtimeID"];
+			self::registerMapping($obj["runtimeID"], $obj["id"], $obj["data"]);
 		}
-
-		self::$legacyIdMap = array_flip(self::$staticRuntimeIdMap);
 	}
 
 	/**
@@ -445,8 +447,9 @@ class BlockFactory{
 	public static function toStaticRuntimeId(int $id, int $meta = 0) : int{
 		$index = ($id << 4) | $meta;
 		if(!isset(self::$staticRuntimeIdMap[$index])){
-			MainLogger::getLogger()->error("ID $id meta $meta does not have a corresponding block runtime ID, returning AIR (0)");
-			return 0;
+			self::registerMapping($rtId = ++self::$lastRuntimeId, $id, $meta);
+			MainLogger::getLogger()->error("ID $id meta $meta does not have a corresponding block static runtime ID, added a new unknown runtime ID ($rtId)");
+			return $rtId;
 		}
 
 		return self::$staticRuntimeIdMap[$index];
@@ -463,4 +466,10 @@ class BlockFactory{
 		$v = self::$legacyIdMap[$runtimeId];
 		return [$v >> 4, $v & 0xf];
 	}
+
+	private static function registerMapping(int $staticRuntimeId, int $legacyId, int $legacyMeta) : void{
+		self::$staticRuntimeIdMap[($legacyId << 4) | $legacyMeta] = $staticRuntimeId;
+		self::$legacyIdMap[$staticRuntimeId] = ($legacyId << 4) | $legacyMeta;
+		self::$lastRuntimeId = max(self::$lastRuntimeId, $staticRuntimeId);
+	}
 }