diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 369ad48..782fecc 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -7,6 +7,9 @@ on:
 jobs:
   release:
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      actions: read
     steps:
       - uses: actions/checkout@v4
 
diff --git a/README.md b/README.md
index 78a79ad..d3665c2 100644
--- a/README.md
+++ b/README.md
@@ -66,6 +66,13 @@ std::cout << "a= " << a << ", b= " << b << '\n';
 numbers::i64 ret = a.saturating_mul(b);
 std::cout << ret << '\n';
 ```
+
+### wrapping add
+```c++
+numbers::u128 max = numbers::u128::MAX;
+numbers::u128 ret = max.wrapping_add(1); // wrapping around
+std::cout << ret << '\n';
+```
 </details>
 
 ## Contribute