diff --git a/README.md b/README.md
index 0a985f1..90e1654 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,8 @@
 ## Toolchain
 
 ```sh
-cargo install espup
+cargo install espup --locked
+cargo install espflash --locked
 espup install  --name book-1.0.0 --toolchain-version 1.90.0
 ```