diff --git a/src/main/java/de/bixilon/minosoft/gui/rendering/chunk/WorldRenderer.kt b/src/main/java/de/bixilon/minosoft/gui/rendering/chunk/WorldRenderer.kt
index 05d686538..4f957c8ed 100644
--- a/src/main/java/de/bixilon/minosoft/gui/rendering/chunk/WorldRenderer.kt
+++ b/src/main/java/de/bixilon/minosoft/gui/rendering/chunk/WorldRenderer.kt
@@ -184,6 +184,7 @@ class WorldRenderer(
 
     override fun draw() {
         shader.use()
+        val visibleChunks = visibleChunks.toSynchronizedMap()
 
         for ((_, map) in visibleChunks) {
             for ((_, mesh) in map) {