diff --git a/cmd/mesh-controller/first_builds.go b/cmd/mesh-controller/first_builds.go
index 64c877de..7283c44f 100644
--- a/cmd/mesh-controller/first_builds.go
+++ b/cmd/mesh-controller/first_builds.go
@@ -202,7 +202,7 @@ func firstBuildObservations(waiting []inventory.BatchedMerge, now time.Time) []c
 	return out
 }
 
-// probeFirstBuilds is D17: no first merge waits past its bound for mesh-delivery's word unsaid.
+// probeFirstBuilds is D18: no first merge waits past its bound for mesh-delivery's word unsaid.
 func probeFirstBuilds(ctx context.Context, d *doctor) ([]conditions.Observation, error) {
 	waiting, err := d.open.inventory.WaitingMerges(ctx)
 	if err != nil {