diff --git a/lexer/src/number.rs b/lexer/src/number.rs
index 2b98585..7bab968 100644
--- a/lexer/src/number.rs
+++ b/lexer/src/number.rs
@@ -2,7 +2,7 @@
  * Eryn Wells <eryn@erynwells.me>
  */
 
-use sibiltypes::Number;
+use sibiltypes::number::{Number, Exact};
 
 #[derive(Debug)]
 pub enum Radix { Bin, Oct, Dec, Hex }
@@ -10,12 +10,9 @@ pub enum Radix { Bin, Oct, Dec, Hex }
 #[derive(PartialEq, Debug)]
 pub enum Sign { Pos, Neg }
 
-#[derive(PartialEq, Debug)]
-pub enum Exactness { Exact, Inexact }
-
 #[derive(Debug)]
 pub struct NumberBuilder {
-    exact: Option<Exactness>,
+    exact: Exact,
     radix: Radix,
     sign: Sign,
     value: f64,
@@ -25,7 +22,7 @@ pub struct NumberBuilder {
 impl NumberBuilder {
     pub fn new() -> NumberBuilder {
         NumberBuilder {
-            exact: None,
+            exact: Exact::Yes,
             radix: Radix::Dec,
             sign: Sign::Pos,
             value: 0.0,
@@ -33,8 +30,8 @@ impl NumberBuilder {
         }
     }
 
-    pub fn exact<'a>(&'a mut self, ex: Exactness) -> &'a mut NumberBuilder {
-        self.exact = Some(ex);
+    pub fn exact<'a>(&'a mut self, ex: Exact) -> &'a mut NumberBuilder {
+        self.exact = ex;
         self
     }
 
@@ -79,8 +76,7 @@ impl NumberBuilder {
             value
         };
         // TODO: Use an integer if we can.
-        let exact = self.point == 0 || self.exact == Some(Exactness::Exact);
-        Number::from_float(value, exact)
+        Number::from_float(value, self.exact)
     }
 
     pub fn radix_value(&self) -> u32 {
diff --git a/types/src/number/mod.rs b/types/src/number/mod.rs
index 4f9a467..8b90c3b 100644
--- a/types/src/number/mod.rs
+++ b/types/src/number/mod.rs
@@ -17,16 +17,28 @@ pub use self::real::Real;
 type Int = i64;
 type Flt = f64;
 
+#[derive(Debug, Eq, PartialEq)]
+pub enum Exact { Yes, No }
+
+impl fmt::Display for Exact {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", match *self {
+            Exact::Yes => "#e",
+            Exact::No => "#i",
+        })
+    }
+}
+
 // TODO: Implement PartialEq myself cause there are some weird nuances to comparing numbers.
 #[derive(Debug, PartialEq)]
 pub struct Number {
     real: Real,
     imag: Option<Real>,
-    exact: bool,
+    exact: Exact,
 }
 
 impl Number {
-    fn new(real: Real, imag: Option<Real>, exact: bool) -> Number {
+    fn new(real: Real, imag: Option<Real>, exact: Exact) -> Number {
         Number {
             real: real.reduce(),
             imag: imag.map(|n| n.reduce()),
@@ -34,12 +46,12 @@ impl Number {
         }
     }
 
-    pub fn from_int(value: Int, exact: bool) -> Number {
+    pub fn from_int(value: Int, exact: Exact) -> Number {
         Number::new(Real::Integer(value), None, exact)
     }
 
-    pub fn from_quotient(p: Int, q: Int, exact: bool) -> Number {
-        let real = if exact {
+    pub fn from_quotient(p: Int, q: Int, exact: Exact) -> Number {
+        let real = if exact == Exact::Yes {
             // Make an exact rational an integer if possible.
             Real::Rational(p, q).demote()
         }
@@ -50,8 +62,8 @@ impl Number {
         Number::new(real, None, exact)
     }
 
-    pub fn from_float(value: Flt, exact: bool) -> Number {
-        let real = if exact {
+    pub fn from_float(value: Flt, exact: Exact) -> Number {
+        let real = if exact == Exact::Yes {
             // Attempt to demote irrationals.
             Real::Irrational(value).demote()
         }
@@ -61,7 +73,12 @@ impl Number {
         Number::new(real, None, exact)
     }
 
-    pub fn is_exact(&self) -> bool { self.exact }
+    pub fn is_exact(&self) -> bool {
+        match self.exact {
+            Exact::Yes => true,
+            Exact::No => false,
+        }
+    }
 }
 
 impl fmt::Display for Number {
@@ -85,6 +102,6 @@ mod tests {
     #[test]
     fn exact_irrationals_are_reduced() {
         let real = Real::Rational(3, 2);
-        assert_eq!(Number::from_float(1.5, true), Number::new(real, None, true));
+        assert_eq!(Number::from_float(1.5, Exact::Yes), Number::new(real, None, Exact::Yes));
     }
 }