diff --git a/crypto/dalek-ff-group/src/field.rs b/crypto/dalek-ff-group/src/field.rs
index a5baf5d2..2831f69e 100644
--- a/crypto/dalek-ff-group/src/field.rs
+++ b/crypto/dalek-ff-group/src/field.rs
@@ -117,7 +117,7 @@ impl PrimeField for FieldElement {
 
   const S: u32 = 2;
   fn is_odd(&self) -> Choice {
-    unimplemented!()
+    (self.to_repr()[0] & 1).into()
   }
   fn multiplicative_generator() -> Self {
     2u64.into()
@@ -159,6 +159,17 @@ impl FieldElement {
 }
 
 #[test]
+fn test_is_odd() {
+  assert_eq!(0, FieldElement::zero().is_odd().unwrap_u8());
+  assert_eq!(1, FieldElement::one().is_odd().unwrap_u8());
+  assert_eq!(0, FieldElement::one().double().is_odd().unwrap_u8());
+
+  // 0 is even, yet the modulus is odd
+  // -1 moves to the even value before the modulus
+  assert_eq!(0, (-FieldElement::one()).is_odd().unwrap_u8());
+  assert_eq!(1, (-FieldElement::one().double()).is_odd().unwrap_u8());
+}
+
 fn test_edwards_d() {
   let a = -FieldElement(U256::from_u32(121665));
   let b = FieldElement(U256::from_u32(121666));