diff --git a/lib/routing.js b/lib/routing.js
index 6236077..af879e2 100644
--- a/lib/routing.js
+++ b/lib/routing.js
@@ -10,6 +10,7 @@ if (typeof window !== 'undefined') {
 const mapper = new Morph({
   types: {
     bool: v => {
+      if (v == null) return undefined
       if (v === 'false') return false
       return Boolean(v)
     }