diff --git a/README.md b/README.md
index db77a35..42954b6 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@
 
 [![Crate](https://img.shields.io/crates/v/lettre.svg)](https://crates.io/crates/lettre)
 [![Docs](https://docs.rs/lettre/badge.svg)](https://docs.rs/lettre/)
-[![Required Rust version](https://img.shields.io/badge/rustc-1.20-green.svg)]()
+[![Required Rust version](https://img.shields.io/badge/rustc-1.31-green.svg)]()
 [![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE)
 
 [![Gitter](https://badges.gitter.im/lettre/lettre.svg)](https://gitter.im/lettre/lettre?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)