diff --git a/src/types/mod.rs b/src/types/mod.rs
index 2fdf4d8..6439233 100644
--- a/src/types/mod.rs
+++ b/src/types/mod.rs
@@ -2,6 +2,8 @@
  * Eryn Wells <eryn@erynwells.me>
  */
 
+use std::fmt;
+
 pub use self::number::Number;
 
 pub mod number;
@@ -9,6 +11,6 @@ pub mod number;
 pub type Boolean = bool;
 pub type Character = char;
 
-pub trait Value { }
+pub trait Value: fmt::Debug { }
 impl Value for Boolean { }
 impl Value for Character { }