diff --git a/compiler/rustc_mir_transform/src/jump_threading.rs b/compiler/rustc_mir_transform/src/jump_threading.rs
index edcc990f02e8..a8193b7c40c8 100644
--- a/compiler/rustc_mir_transform/src/jump_threading.rs
+++ b/compiler/rustc_mir_transform/src/jump_threading.rs
@@ -645,7 +645,7 @@ impl OpportunitySet {
             debug!(?current, ?succ);
 
             // `succ` must be a successor of `current`. If it is not, this means this TO is not
-            // satisfiable, so we bail out.
+            // satisfiable and a previous TO erased this edge, so we bail out.
             if basic_blocks[current].terminator().successors().find(|s| *s == succ).is_none() {
                 debug!("impossible");
                 return;