diff --git a/tests/const_fn.rs b/tests/const_fn.rs
new file mode 100644
index 0000000000000..d9b41b8073c70
--- /dev/null
+++ b/tests/const_fn.rs
@@ -0,0 +1,3 @@
+#[cfg(target_os = "linux")]
+const _FOO: libc::c_uint = unsafe { libc::CMSG_SPACE(1) };
+//^ if CMSG_SPACE is not const, this will fail to compile