diff --git a/setup-toolchain.sh b/setup-toolchain.sh
index 89de40d40..c9d0b8623 100755
--- a/setup-toolchain.sh
+++ b/setup-toolchain.sh
@@ -6,8 +6,15 @@ set -e
 cd "$(dirname "$0")"
 
 if [[ "$CI" == true ]] || ! command -v rustup-toolchain-install-master > /dev/null; then
-  cargo install -Z install-upgrade rustup-toolchain-install-master --bin rustup-toolchain-install-master
+    cargo install -Z install-upgrade rustup-toolchain-install-master --bin rustup-toolchain-install-master
 fi
 
-rustup-toolchain-install-master -f -n master -c rustc-dev
+RUST_COMMIT=$(git ls-remote https://github.com/rust-lang/rust master | awk '{print $1}')
+
+if rustc +master -Vv 2>/dev/null | grep -q "$RUST_COMMIT"; then
+    echo "info: master toolchain is up-to-date"
+    exit 0
+fi
+
+rustup-toolchain-install-master -f -n master -c rustc-dev -- "$RUST_COMMIT"
 rustup override set master