diff --git a/src/lib.rs b/src/lib.rs
index fc20b13..a5ff7bd 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -161,7 +161,7 @@ impl ops::Neg for Fraction {
 
 impl fmt::Display for Fraction {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if self.num == 1 {
+        if self.den == 1 {
             return write!(f, "{0}", self.num);
         } else {
             return write!(f, "{0}/{1}", self.num, self.den);