diff --git a/xtask/src/main.rs b/xtask/src/main.rs
index c52902bb56..4201c6a6a7 100644
--- a/xtask/src/main.rs
+++ b/xtask/src/main.rs
@@ -20,7 +20,7 @@ use xtask::{
 };
 
 // Latest stable, feel free to send a PR if this lags behind.
-const REQUIRED_RUST_VERSION: u32 = 39;
+const REQUIRED_RUST_VERSION: u32 = 40;
 
 struct InstallOpt {
     client: Option<ClientOpt>,