diff --git a/libs/backends/alsa/alsa_audiobackend.cc b/libs/backends/alsa/alsa_audiobackend.cc
index ffb1f6a6fa..55a81632e2 100644
--- a/libs/backends/alsa/alsa_audiobackend.cc
+++ b/libs/backends/alsa/alsa_audiobackend.cc
@@ -489,7 +489,7 @@ AlsaAudioBackend::update_systemic_midi_latencies ()
 		assert (nfo);
 		LatencyRange lr;
 		lr.min = lr.max = (_measure_latency ? 0 : nfo->systemic_output_latency);
-		set_latency_range (boost::dynamic_pointer_cast<AlsaAudioPort>(*it), true, lr);
+		set_latency_range (*it, true, lr);
 	}
 
 	i = 0;