diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 4893e05badcb..a062fbda5bad 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -1765,7 +1765,7 @@ assert_eq!((-a).mod_euc(-b), 1);
             pub fn mod_euc(self, rhs: Self) -> Self {
                 let r = self % rhs;
                 if r < 0 {
-                    if rhs.is_negative() {
+                    if rhs < 0 {
                         r - rhs
                     } else {
                         r + rhs