diff --git a/packages/@posva/vuefire-core/src/firestore/utils.ts b/packages/@posva/vuefire-core/src/firestore/utils.ts
index 3fb3c6c5..1d4edad1 100644
--- a/packages/@posva/vuefire-core/src/firestore/utils.ts
+++ b/packages/@posva/vuefire-core/src/firestore/utils.ts
@@ -69,7 +69,8 @@ export function extractRefs(
           key in oldDoc &&
           // only copy refs if they were refs before
           // https://github.com/vuejs/vuefire/issues/831
-          typeof oldDoc[key] != 'string'
+          typeof oldDoc[key] != 'string' && 
+          oldDoc[key] !== null
             ? oldDoc[key]
             : ref.path
         // TODO: handle subpathes?