diff --git a/node-tools/internal/bus/bus.go b/node-tools/internal/bus/bus.go
index 0e25931..ddf22ce 100644
--- a/node-tools/internal/bus/bus.go
+++ b/node-tools/internal/bus/bus.go
@@ -883,8 +883,9 @@ func (c *Conn) ConsumeAs(module string, deliver func(Envelope) error) (func(), e
 		// (30 seconds) is for a runtime that died, not a handler that is slow — the runtime gives a handler
 		// launch.EventTimeout. Without it an event handled longer than the ack wait was offered again while
 		// it was handled, and counted toward max-deliver (novox/hq issue 387).
-		done := make(chan struct{})
+		done, stopped := make(chan struct{}), make(chan struct{})
 		go func() {
+			defer close(stopped)
 			tick := time.NewTicker(EventHeartbeat)
 			defer tick.Stop()
 			for {
@@ -898,6 +899,8 @@ func (c *Conn) ConsumeAs(module string, deliver func(Envelope) error) (func(), e
 		}()
 		err := deliver(env)
 		close(done)
+		// No in-progress after the answer: one after a Nak would stretch its delay to the whole ack wait.
+		<-stopped
 		if err != nil {
 			_ = msg.NakWithDelay(NakDelay)
 			return