diff --git a/e.rs b/e.rs
index 7ca3efe..3a363be 100644
--- a/e.rs
+++ b/e.rs
@@ -1,7 +1,15 @@
-#![feature(main)]
-#[main]
+#[cfg(feature = "functional")]
+fn e() {
+    std::iter::repeat('e').for_each(|e| print!("{}", e))
+}
+
+#[cfg(not(feature = "functional"))]
 fn e() {
     loop {
         print!("e");
     }
 }
+
+fn main() {
+    e();
+}