diff --git a/src/network/mcpe/convert/RuntimeBlockMapping.php b/src/network/mcpe/convert/RuntimeBlockMapping.php
index 54002ed50..9c4b08536 100644
--- a/src/network/mcpe/convert/RuntimeBlockMapping.php
+++ b/src/network/mcpe/convert/RuntimeBlockMapping.php
@@ -161,6 +161,6 @@ final class RuntimeBlockMapping{
 	 * @phpstan-return CacheableNbt<\pocketmine\nbt\tag\ListTag>
 	 */
 	public function getStartGamePaletteCache() : CacheableNbt{
-		return $this->startGamePaletteCache ?? new CacheableNbt(new ListTag($this->bedrockKnownStates));
+		return $this->startGamePaletteCache ?? ($this->startGamePaletteCache = new CacheableNbt(new ListTag($this->bedrockKnownStates)));
 	}
 }