diff --git a/src/kernel/synch.rs b/src/kernel/synch.rs
index 6ce265b..2ba4e40 100644
--- a/src/kernel/synch.rs
+++ b/src/kernel/synch.rs
@@ -26,7 +26,7 @@ impl Semaphore {
     /// - *counter* initial value of counter
     /// - *thread_manager* Thread manager which managing threads
     pub fn new(counter: i32) -> Semaphore{
-        Semaphore { counter, waiting_queue: List::new()}
+        Semaphore { counter, waiting_queue: List::default() }
     }
 
     ///     Decrement the value, and wait if it becomes < 0. Checking the
@@ -98,7 +98,7 @@ impl Lock {
     /// ### Parameters
     /// - **thread_manager** Thread manager which managing threads
     pub fn new() -> Lock {
-        Lock { owner: None, waiting_queue: List::new(), free: true }
+        Lock { owner: None, waiting_queue: List::default(), free: true }
     }
 
     ///    Wait until the lock become free.  Checking the
@@ -196,7 +196,7 @@ impl Condition {
     /// ### Parameters
     /// - *thread_manager* Thread manager which managing threads
     pub fn new() -> Condition {
-        Condition{ waiting_queue: List::new()}
+        Condition{ waiting_queue: List::default()}
     }
 
     ///  Block the calling thread (put it in the wait queue).
diff --git a/src/kernel/thread_manager.rs b/src/kernel/thread_manager.rs
index 0216663..298d6cf 100644
--- a/src/kernel/thread_manager.rs
+++ b/src/kernel/thread_manager.rs
@@ -28,8 +28,8 @@ impl ThreadManager {
         Self { 
             g_current_thread: Option::None, 
             g_thread_to_be_destroyed: Option::None, 
-            g_alive: List::new(),
-            ready_list: List::new(),
+            g_alive: List::default(),
+            ready_list: List::default(),
         }
     }
 
diff --git a/src/utility/list.rs b/src/utility/list.rs
index 756112a..9fb41bd 100644
--- a/src/utility/list.rs
+++ b/src/utility/list.rs
@@ -31,16 +31,11 @@ pub struct IterMut<'a, T> {
 
 impl<T: PartialEq> List<T> {
 
-    /// Create an empty list
-    pub fn new() -> Self {
-        List { head: ptr::null_mut(), tail: ptr::null_mut() }
-    }
-
     /// Push an item at the end of the list
     pub fn push(&mut self, elem: T) {
         unsafe {
             let new_tail = Box::into_raw(Box::new(Node {
-                elem: elem,
+                elem,
                 next: ptr::null_mut(),
             }));
 
@@ -97,10 +92,12 @@ impl<T: PartialEq> List<T> {
     /// Worst case complexity of this function is O(n)
     pub fn contains(&self, elem: &T) -> bool {
         let mut iter = self.iter();
-        let element = iter.next();
+        let mut element = iter.next();
         while element.is_some() {
             if element.unwrap() == elem {
                 return true;
+            } else {
+                element = iter.next();
             }
         }
         false
@@ -159,9 +156,16 @@ impl<T: PartialEq> List<T> {
     }
 }
 
+impl<T: PartialEq> Default for List<T> {
+    /// Create an empty list
+    fn default() -> Self {
+        Self { head: ptr::null_mut(), tail: ptr::null_mut() }
+    }
+}
+
 impl<T: PartialEq> Drop for List<T> {
     fn drop(&mut self) {
-        while let Some(_) = self.pop() {} // removing every item from list (necessary as we using unsafe function)
+        while self.pop().is_some() {} // removing every item from list (necessary as we using unsafe function)
     }
 }
 
@@ -207,7 +211,7 @@ mod test {
 
     #[test]
     fn basics() {
-        let mut list = List::new();
+        let mut list = List::default();
 
         // Check empty list behaves right
         assert_eq!(list.pop(), None);
@@ -236,7 +240,7 @@ mod test {
 
     #[test]
     fn peek() {
-        let mut list = List::new();
+        let mut list = List::default();
         assert_eq!(list.peek(), None);
         assert_eq!(list.peek_mut(), None);
         list.push(1); 
@@ -249,7 +253,7 @@ mod test {
 
     #[test]
     fn into_iter() {
-        let mut list = List::new();
+        let mut list = List::default();
         list.push(1);
         list.push(2);
         list.push(3);
@@ -263,7 +267,7 @@ mod test {
 
     #[test]
     fn iter() {
-        let mut list = List::new();
+        let mut list = List::default();
         list.push(1);
         list.push(2);
         list.push(3);
@@ -276,8 +280,10 @@ mod test {
 
     #[test]
     fn iter_mut() {
-        let mut list = List::new();
-        list.push(1); list.push(2); list.push(3);
+        let mut list = List::default();
+        list.push(1);
+        list.push(2);
+        list.push(3);
 
         let mut iter = list.iter_mut();
         assert_eq!(iter.next(), Some(&mut 1));
@@ -285,9 +291,37 @@ mod test {
         assert_eq!(iter.next(), Some(&mut 3));
     }
 
+    #[test]
+    fn contains_test() {
+        let mut list = List::default();
+        assert_eq!(list.peek(), None);
+        list.push(1);
+        list.push(2);
+        list.push(3);
+
+        assert_eq!(list.contains(&1), true);
+        assert_eq!(list.contains(&4), false);
+    }
+
+    #[test]
+    fn remove_test() {
+        let mut list = List::default();
+        assert_eq!(list.peek(), None);
+        list.push(1);
+        list.push(2);
+        list.push(3);
+
+        assert_eq!(list.contains(&2), true);
+        list.remove(&2);
+        assert_eq!(list.contains(&2), false);
+        assert_eq!(list.pop(), Option::Some(1));
+        assert_eq!(list.pop(), Option::Some(3));
+        assert_eq!(list.pop(), Option::None);
+    }
+
     #[test]
     fn miri_test() {
-        let mut list = List::new();
+        let mut list = List::default();
 
         list.push(1);
         list.push(2);