diff --git a/src/eval.rs b/src/eval.rs
index d2a269d..3029f1e 100644
--- a/src/eval.rs
+++ b/src/eval.rs
@@ -8,7 +8,6 @@ struct Varmap {
 impl Varmap {
     fn new() -> Varmap {
         let mut map = HashMap::new();
-        map.insert("a".to_string(), Expression::Number(10.0));
         Varmap { map: map }
     }