diff --git a/src/executor.rs b/src/executor.rs
index 2ec21a7..fefe6c7 100644
--- a/src/executor.rs
+++ b/src/executor.rs
@@ -15,9 +15,10 @@ pub struct Executor<F, const N: usize> {
 }
 
 impl<F: Future, const N: usize> Executor<F, N> {
+    const SAMPLE: Option<F> = None;
     pub fn new() -> Self {
         Executor {
-            task_queue: [None; N],
+            task_queue: [Self::SAMPLE; N],
         }
     }
 
diff --git a/src/main.rs b/src/main.rs
index 605a784..9961ae1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,3 @@
-#![feature(const_generics)]
-#![feature(const_in_array_repeat_expressions)]
-
 use std::rc::Rc;
 use std::time::Instant;
 use structopt::StructOpt;