diff --git a/src/main/java/com/yyon/grapplinghook/client/ClientSetup.java b/src/main/java/com/yyon/grapplinghook/client/ClientSetup.java
index 41c44ce..b85a983 100644
--- a/src/main/java/com/yyon/grapplinghook/client/ClientSetup.java
+++ b/src/main/java/com/yyon/grapplinghook/client/ClientSetup.java
@@ -62,7 +62,9 @@ public static KeyMapping createKeyBinding(KeyMapping k) {
 	@SubscribeEvent
 	public static void clientSetup(final FMLClientSetupEvent event) {
 	    instance = new ClientSetup();
-	    instance.onClientSetup();
+            // The onclientSetup method calls ItemProperties::register which is
+            // not thread-safe, so enqueue it.
+	    event.enqueueWork(instance::onClientSetup);
 	}
 	
 	private static class GrapplehookEntityRenderFactory implements EntityRendererProvider<GrapplehookEntity> {