diff --git a/libs/ardour/ardour/ladspa_plugin.h b/libs/ardour/ardour/ladspa_plugin.h
index 0dd7f9efac..6853a1dc36 100644
--- a/libs/ardour/ardour/ladspa_plugin.h
+++ b/libs/ardour/ardour/ladspa_plugin.h
@@ -113,7 +113,7 @@ class LadspaPlugin : public ARDOUR::Plugin
 	LADSPA_Properties           properties() const                { return _descriptor->Properties; }
 	uint32_t                    index() const                     { return _index; }
 	const char *                copyright() const                 { return _descriptor->Copyright; }
-	LADSPA_PortDescriptor       port_descriptor(uint32_t i) const { return _descriptor->PortDescriptors[i]; }
+	LADSPA_PortDescriptor       port_descriptor(uint32_t i) const;
 	const LADSPA_PortRangeHint* port_range_hints() const          { return _descriptor->PortRangeHints; }
 	const char * const *        port_names() const                { return _descriptor->PortNames; }
 
diff --git a/libs/ardour/ladspa_plugin.cc b/libs/ardour/ladspa_plugin.cc
index b9400dd8d8..3a25eab384 100644
--- a/libs/ardour/ladspa_plugin.cc
+++ b/libs/ardour/ladspa_plugin.cc
@@ -916,3 +916,16 @@ LadspaPlugin::do_save_preset (string name)
 	return uri;
 }
 
+LADSPA_PortDescriptor
+LadspaPlugin::port_descriptor (uint32_t i) const
+{
+	if (i < _descriptor->PortCount) {		
+		return _descriptor->PortDescriptors[i];
+	}
+	
+	warning << "LADSPA plugin port index " << i << " out of range." << endmsg;
+	return 0;
+}
+
+		
+