diff --git a/src/edwards.rs b/src/edwards.rs
index 102a5ea3e..3b65e2561 100644
--- a/src/edwards.rs
+++ b/src/edwards.rs
@@ -450,6 +450,10 @@ impl EdwardsPoint {
     /// Convert this `EdwardsPoint` on the Edwards model to the
     /// corresponding `MontgomeryPoint` on the Montgomery model.
     ///
+    /// This function has one exceptional case; the identity point of
+    /// the Edwards curve is sent to the 2-torsion point \\((0,0)\\)
+    /// on the Montgomery curve.
+    ///
     /// Note that this is a one-way conversion, since the Montgomery
     /// model does not retain sign information.
     pub fn to_montgomery(&self) -> MontgomeryPoint {
@@ -457,7 +461,7 @@ impl EdwardsPoint {
         //
         // The denominator is zero only when y=1, the identity point of
         // the Edwards curve.  Since 0.invert() = 0, in this case we
-        // compute u = 0, the identity point of the Montgomery line.
+        // compute the 2-torsion point (0,0).
         let U = &self.Z + &self.Y;
         let W = &self.Z - &self.Y;
         let u = &U * &W.invert();