diff --git a/README.md b/README.md
index be9256a4..113436c1 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,8 @@
 
 [<img alt="docs.rs" src="https://img.shields.io/badge/docs.rs-skl-66c2a5?style=for-the-badge&labelColor=555555&logo=data:image/svg+xml;base64,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" height="20">][doc-url]
 [<img alt="crates.io" src="https://img.shields.io/crates/v/skl?style=for-the-badge&logo=data:image/svg+xml;base64,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" height="22">][crates-url]
+
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 <img alt="license" src="https://img.shields.io/badge/License-Apache%202.0/MIT-blue.svg?style=for-the-badge&fontColor=white&logoColor=f5c076&logo=data:image/svg+xml;base64,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" height="22">
 
 1. A lock-free thread-safe concurrent `SkipMap` and `SkipSet` implementation based on ARENA skiplist which helps develop MVCC memtable for LSM-Tree.