diff --git a/libs/backends/alsa/alsa_audiobackend.cc b/libs/backends/alsa/alsa_audiobackend.cc
index 111108af1a..4d21c828bc 100644
--- a/libs/backends/alsa/alsa_audiobackend.cc
+++ b/libs/backends/alsa/alsa_audiobackend.cc
@@ -1732,6 +1732,7 @@ AlsaAudioBackend::set_latency_range (PortEngine::PortHandle port_handle, bool fo
 	BackendPortPtr port = boost::dynamic_pointer_cast<BackendPort> (port_handle);
 	if (!valid_port (port)) {
 		DEBUG_TRACE (PBD::DEBUG::BackendPorts, "AlsaPort::set_latency_range (): invalid port.");
+		return;
 	}
 	port->set_latency_range (latency_range, for_playback);
 }
diff --git a/libs/backends/dummy/dummy_audiobackend.cc b/libs/backends/dummy/dummy_audiobackend.cc
index 7f3abd8dee..8c96b2ff59 100644
--- a/libs/backends/dummy/dummy_audiobackend.cc
+++ b/libs/backends/dummy/dummy_audiobackend.cc
@@ -873,6 +873,7 @@ DummyAudioBackend::set_latency_range (PortEngine::PortHandle port_handle, bool f
 	BackendPortPtr port = boost::dynamic_pointer_cast<BackendPort> (port_handle);
 	if (!valid_port (port)) {
 		DEBUG_TRACE (PBD::DEBUG::BackendPorts, "DummyPort::set_latency_range (): invalid port.");
+		return;
 	}
 	port->set_latency_range (latency_range, for_playback);
 }
diff --git a/libs/backends/portaudio/portaudio_backend.cc b/libs/backends/portaudio/portaudio_backend.cc
index f0d2f5e158..bd251d87fa 100644
--- a/libs/backends/portaudio/portaudio_backend.cc
+++ b/libs/backends/portaudio/portaudio_backend.cc
@@ -1407,6 +1407,7 @@ PortAudioBackend::set_latency_range (PortEngine::PortHandle port_handle, bool fo
 	boost::shared_ptr<BackendPort> port = boost::dynamic_pointer_cast<BackendPort>(port_handle);
 	if (!valid_port (port)) {
 		DEBUG_PORTS("BackendPort::set_latency_range (): invalid port.\n");
+		return;
 	}
 	port->set_latency_range (latency_range, for_playback);
 }