diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index 53d31e8..43edfb9 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -85,9 +85,9 @@ impl PreToken {
 				return Ok(match &s[..] {
 					// Mathematical constants
 					// 100 digits of each.
-					"π"|"pi" => { Token::Constant(Quantity::new_float_from_string("3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067"), String::from("π")) },
-					"e" => { Token::Constant(Quantity::new_float_from_string("2.718281828459045235360287471352662497757247093699959574966967627724076630353547594571382178525166427"), String::from("e")) },
-					"phi"|"φ" => { Token::Constant(Quantity::new_float_from_string("1.618033988749894848204586834365638117720309179805762862135448622705260462818902449707207204189391137"), String::from("φ")) },
+					"π"|"pi" => { Token::Constant(Quantity::new_float_from_string("3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067").unwrap(), String::from("π")) },
+					"e" => { Token::Constant(Quantity::new_float_from_string("2.718281828459045235360287471352662497757247093699959574966967627724076630353547594571382178525166427").unwrap(), String::from("e")) },
+					"phi"|"φ" => { Token::Constant(Quantity::new_float_from_string("1.618033988749894848204586834365638117720309179805762862135448622705260462818902449707207204189391137").unwrap(), String::from("φ")) },
 
 					_ => { return Err((l, ParserError::Undefined(s))); }
 				});
diff --git a/src/quantity/quantity.rs b/src/quantity/quantity.rs
index 6a9f3b6..7fbb62f 100644
--- a/src/quantity/quantity.rs
+++ b/src/quantity/quantity.rs
@@ -102,11 +102,17 @@ impl Quantity {
 		}
 	}
 
-	pub fn new_float_from_string(s: &str) -> Quantity {
+	pub fn new_float_from_string(s: &str) -> Option<Quantity> {
 		let v = Float::parse(s);
-		return Quantity::Float {
-			v: Float::with_val(FLOAT_PRECISION, v.unwrap())
-		}
+
+		let v = match v {
+			Ok(x) => x,
+			Err(_) => return None
+		};
+
+		return Some(Quantity::Float {
+			v: Float::with_val(FLOAT_PRECISION, v)
+		})
 	}
 
 
@@ -189,6 +195,7 @@ impl Quantity {
 	}
 
 	quick_quant_fn!(fract);
+	quick_quant_fn!(exp);
 
 	quick_quant_fn!(abs);
 	quick_quant_fn!(floor);
diff --git a/src/quantity/rationalq.rs b/src/quantity/rationalq.rs
index 5916224..a4c47a0 100644
--- a/src/quantity/rationalq.rs
+++ b/src/quantity/rationalq.rs
@@ -86,6 +86,8 @@ impl RationalQ {
 	}
 
 
+	pub fn exp(&self) -> Quantity {float!(self.to_float().exp())}
+
 	pub fn abs(&self) -> Quantity {rational!(self.val.clone().abs())}
 	pub fn floor(&self) -> Quantity {rational!(self.val.clone().floor())}
 	pub fn ceil(&self) -> Quantity {rational!(self.val.clone().ceil())}