diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index ecb71c74a1..e5b7f195a4 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -3455,11 +3455,16 @@ Session::add_routes_inner (RouteList& new_routes, bool input_auto_connect, bool
 			}
 		}
 
+#ifndef __APPLE__
+		/* clang complains: 'operator<<' should be declared prior to the call site or in an associated namespace of one of its
+		 * arguments std::ostream& operator<<(std::ostream& o, ARDOUR::PresentationInfo const& rid)"
+		 */
 		DEBUG_TRACE (DEBUG::OrderKeys, string_compose ("added route %1, group order %2 type %3 (summary: %4)\n",
 		                                               r->name(),
 		                                               r->presentation_info().order(),
 		                                               enum_2_string (r->presentation_info().flags()),
 		                                               r->presentation_info()));
+#endif
 
 
 		if (input_auto_connect || output_auto_connect) {