diff --git a/gstlal-ugly/gst/framecpp/framecpp_channelmux.cc b/gstlal-ugly/gst/framecpp/framecpp_channelmux.cc
index 52cbd406f1906cbd2c88720ac323ceeaf9091f0e..571a18e0f8548973753f435de06ac768af35651f 100644
--- a/gstlal-ugly/gst/framecpp/framecpp_channelmux.cc
+++ b/gstlal-ugly/gst/framecpp/framecpp_channelmux.cc
@@ -1089,6 +1089,9 @@ static gboolean sink_event(GstPad *pad, GstObject *parent, GstEvent *event)
 
 	case GST_EVENT_EOS:
 		GST_LOG_OBJECT(mux, "EOS");
+#if __GNUC__ >= 7
+		__attribute__ ((fallthrough));
+#endif
 	case GST_EVENT_FLUSH_START:
 		flush(mux);
 		break;