diff --git a/src/index.js b/src/index.js
index 628e61f4..1da7289e 100644
--- a/src/index.js
+++ b/src/index.js
@@ -43,6 +43,7 @@ export {
   snapshot,
   emptySnapshot,
   findRootTypeKey,
+  findIndexSS,
   getItem,
   typeListToArraySnapshot,
   typeMapGetSnapshot,