diff --git a/.envrc b/.envrc
index 8643617f..935a201a 100644
--- a/.envrc
+++ b/.envrc
@@ -1,5 +1,6 @@
 watch_file shell.nix
 watch_file flake.lock
+watch_file rust-toolchain.toml
 
 # try to use flakes, if it fails use normal nix (ie. shell.nix)
 use flake || use nix