diff --git a/src/ir/term/mod.rs b/src/ir/term/mod.rs
index 09d90dad6..d436ab8c6 100644
--- a/src/ir/term/mod.rs
+++ b/src/ir/term/mod.rs
@@ -131,9 +131,12 @@ pub enum Op {
     /// A random value, sampled uniformly and independently of its arguments.
     ///
     /// Takes a name (if deterministically sampled, challenges of different names are sampled
-    /// differentely) and a field to sample from.
+    /// differently) and a field to sample from.
     ///
     /// In IR evaluation, we sample deterministically based on a hash of the name.
+    ///
+    /// In an multi-round SNARK context, we set this based on hashing commitments
+    /// to the witnesses for previous rounds.
     PfChallenge(Box<ChallengeOp>),
     /// Requires the input pf element to fit in this many (unsigned) bits.
     PfFitsInBits(usize),