diff --git a/karax/karax.nim b/karax/karax.nim
index 77befcd..0b1da6c 100644
--- a/karax/karax.nim
+++ b/karax/karax.nim
@@ -31,7 +31,7 @@ type
 
   KaraxInstance* = ref object ## underlying karax instance. Usually you don't have
                               ## know about this.
-    rootId: cstring not nil
+    rootId: cstring
     renderer: proc (data: RouterData): VNode {.closure.}
     currentTree: VNode
     postRenderCallback: proc (data: RouterData)