diff --git a/roomserver/internal/input/input.go b/roomserver/internal/input/input.go
index a94371981..ae2674c62 100644
--- a/roomserver/internal/input/input.go
+++ b/roomserver/internal/input/input.go
@@ -310,7 +310,8 @@ func (w *worker) _next() {
 	msg := msgs[0]
 	var inputRoomEvent api.InputRoomEvent
 	if err = json.Unmarshal(msg.Data, &inputRoomEvent); err != nil {
-		_ = msg.Term()
+		// using AckWait here makes the call synchronous; 5 seconds is default value
+		_ = msg.Term(nats.AckWait(time.Second * 5))
 		return
 	}
 
@@ -346,10 +347,15 @@ func (w *worker) _next() {
 				"type":     inputRoomEvent.Event.Type(),
 			}).Warn("Roomserver failed to process event")
 		}
-		_ = msg.Term()
+		// Even though we failed to process this message (e.g. due to Dendrite restarting and receiving a context canceled),
+		// the message may already have been queued for redelivery or will be, so this makes sure that we still reprocess the msg
+		// after restarting. We only Ack if the context was not yet canceled.
+		if w.r.ProcessContext.Context().Err() == nil {
+			_ = msg.AckSync()
+		}
 		errString = err.Error()
 	} else {
-		_ = msg.Ack()
+		_ = msg.AckSync()
 	}
 
 	// If it was a synchronous input request then the "sync" field