diff --git a/.cirrus.yml b/.cirrus.yml
index a0ecc03b95..3f3f1e1f34 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -14,3 +14,4 @@ task:
   test_script:
     - . $HOME/.cargo/env
     - cargo build --all
+# FOO
diff --git a/rust-version b/rust-version
new file mode 100644
index 0000000000..b2bed194c1
--- /dev/null
+++ b/rust-version
@@ -0,0 +1 @@
+631bac0cee361142bf378a425032b50d17364164