diff --git a/2018/src/common.rs b/2018/src/common.rs
index 880400f..ce2ea2f 100644
--- a/2018/src/common.rs
+++ b/2018/src/common.rs
@@ -35,10 +35,10 @@ pub fn prime_sieve(dest: &mut[bool]) {
 /// be easily run from the main program.
 pub trait Solution {
     /// Solve the first part of the day
-    fn part1(&mut self, input: Box<io::Read>);
+    fn part1(&mut self, input: &mut io::Read) -> String;
 
     /// Solve the second part of the day
-    fn part2(&mut self, input: Box<io::Read>);
+    fn part2(&mut self, input: &mut io::Read) -> String;
 }
 
 #[cfg(test)]
diff --git a/2018/src/day1.rs b/2018/src/day1.rs
index bf413b9..fdaff75 100644
--- a/2018/src/day1.rs
+++ b/2018/src/day1.rs
@@ -11,11 +11,11 @@ impl Day1 {
 }
 
 impl common::Solution for Day1 {
-    fn part1(&mut self, input: Box<io::Read>) {
-        println!("Not implemented");
+    fn part1(&mut self, input: &mut io::Read) -> String {
+        panic!("Not implemented");
     }
 
-    fn part2(&mut self, input: Box<io::Read>) {
-        println!("Not implemented");
+    fn part2(&mut self, input: &mut io::Read) -> String {
+        panic!("Not implemented");
     }
 }
diff --git a/2018/src/main.rs b/2018/src/main.rs
index 5e373e6..1c38dc1 100644
--- a/2018/src/main.rs
+++ b/2018/src/main.rs
@@ -38,15 +38,15 @@ fn main() {
     let day: i32 = (&matches.value_of("day").unwrap()).parse()
         .expect("Invalid int");
     let mut implementation = get_impl(day);
-    let data: Box<io::Read> = match matches.value_of("input") {
+    let mut data: Box<io::Read> = match matches.value_of("input") {
         Some(filename) => { Box::new(fs::File::open(filename).unwrap()) }
         None => { Box::new(io::stdin()) }
     };
 
     if matches.is_present("part2") {
-        implementation.part2(data)
+        println!("{}", implementation.part2(&mut data));
     } else {
-        implementation.part1(data)
+        println!("{}", implementation.part1(&mut data));
     }
 }