diff --git a/rust-toolchain b/rust-toolchain
new file mode 100644
index 0000000000000000000000000000000000000000..a50908ca3daf95eba6210f0cc2c11c49f7bc1c9e
--- /dev/null
+++ b/rust-toolchain
@@ -0,0 +1 @@
+1.42.0