diff --git a/rust-version b/rust-version
index 13526a3fac..d5ddd1d037 100644
--- a/rust-version
+++ b/rust-version
@@ -1 +1 @@
-043eca7f0b34d12e61c44206beca740628647080
+c38ddb8040edce1b05bc09a0e8439472e9f67623
diff --git a/tests/run-pass/available-concurrency.rs b/tests/run-pass/available-concurrency.rs
new file mode 100644
index 0000000000..5f3121ca8a
--- /dev/null
+++ b/tests/run-pass/available-concurrency.rs
@@ -0,0 +1,5 @@
+#![feature(available_concurrency)]
+
+fn main() {
+    assert_eq!(std::thread::available_concurrency().unwrap().get(), 1);
+}