diff --git a/src/evaluate/function.rs b/src/evaluate/function.rs
index 579032e..8aacd9d 100644
--- a/src/evaluate/function.rs
+++ b/src/evaluate/function.rs
@@ -28,7 +28,7 @@ fn to_radians(q: Quantity) -> Result<Quantity, ()> {
 
 pub fn eval_function(g: &Expression) -> Result<Expression, (LineLocation, EvalError)> {
 
-	let Expression::Operator(loc, Operator::Function(f), args) = g else {panic!()};
+	let Expression::Operator(loc, Operator::Function(f), args) = g else {unreachable!()};
 
 	if args.len() != 1 {panic!()};
 	let a = &args[0];
diff --git a/src/evaluate/mod.rs b/src/evaluate/mod.rs
index d9078b6..18f6831 100644
--- a/src/evaluate/mod.rs
+++ b/src/evaluate/mod.rs
@@ -11,8 +11,8 @@ pub enum EvalError {
 	ZeroDivision,
 	IncompatibleUnit,
 	IncompatibleUnits(String, String),
-	BadDefineName,
-	Undefined(String)
+	Undefined(String),
+	EvaluationError,
 }
 
 
@@ -32,13 +32,13 @@ impl ToString for EvalError {
 				String::from("Incompatible unit")
 			},
 			EvalError::IncompatibleUnits(a, b) => {
-				format!("Incompatible units ({} and {})", a, b)
-			},
-			EvalError::BadDefineName => {
-				String::from("Invalid variable name")
+				format!("Incompatible units ({a} and {b})")
 			},
 			EvalError::Undefined(s) => {
-				format!("{} is undefined", s)
+				format!("{s} is undefined")
+			},
+			EvalError::EvaluationError => {
+				String::from("Could not evaluate")
 			}
 		}
 	}