diff --git a/libs/ardour/ardour/bundle.h b/libs/ardour/ardour/bundle.h
index cf035133ea..00a661999d 100644
--- a/libs/ardour/ardour/bundle.h
+++ b/libs/ardour/ardour/bundle.h
@@ -178,8 +178,8 @@ public:
 	int channel; ///< channel index, or -1 for "all"
 };
 
+std::ostream & operator<< (std::ostream & o, Bundle const &);
+
 }
 
-std::ostream & operator<< (std::ostream & o, ARDOUR::Bundle const &);
-
 #endif /* __ardour_bundle_h__ */
diff --git a/libs/ardour/ardour/chan_count.h b/libs/ardour/ardour/chan_count.h
index a62d5dc70f..438d5abaa1 100644
--- a/libs/ardour/ardour/chan_count.h
+++ b/libs/ardour/ardour/chan_count.h
@@ -212,9 +212,9 @@ private:
 	uint32_t _counts[DataType::num_types];
 };
 
-} // namespace ARDOUR
+LIBARDOUR_API std::ostream& operator<<(std::ostream& o, const ChanCount& c);
 
-LIBARDOUR_API std::ostream& operator<<(std::ostream& o, const ARDOUR::ChanCount& c);
+} // namespace ARDOUR
 
 #endif // __ardour_chan_count_h__
 
diff --git a/libs/ardour/ardour/chan_mapping.h b/libs/ardour/ardour/chan_mapping.h
index 21838a1221..ef7344c9ed 100644
--- a/libs/ardour/ardour/chan_mapping.h
+++ b/libs/ardour/ardour/chan_mapping.h
@@ -136,9 +136,9 @@ private:
 	Mappings _mappings;
 };
 
-} // namespace ARDOUR
+std::ostream& operator<<(std::ostream& o, const ChanMapping& m);
 
-std::ostream& operator<<(std::ostream& o, const ARDOUR::ChanMapping& m);
+} // namespace ARDOUR
 
 #endif // __ardour_chan_mapping_h__
 
diff --git a/libs/ardour/ardour/plugin_insert.h b/libs/ardour/ardour/plugin_insert.h
index 8b4b55f6e4..22a0ac98c1 100644
--- a/libs/ardour/ardour/plugin_insert.h
+++ b/libs/ardour/ardour/plugin_insert.h
@@ -447,8 +447,8 @@ private:
 	GATOMIC_QUAL gint _flush;
 };
 
+std::ostream& operator<<(std::ostream& o, const PluginInsert::Match& m);
+
 } // namespace ARDOUR
 
-std::ostream& operator<<(std::ostream& o, const ARDOUR::PluginInsert::Match& m);
-
 #endif /* __ardour_plugin_insert_h__ */
diff --git a/libs/ardour/ardour/presentation_info.h b/libs/ardour/ardour/presentation_info.h
index 023b947730..05da7bb0a3 100644
--- a/libs/ardour/ardour/presentation_info.h
+++ b/libs/ardour/ardour/presentation_info.h
@@ -280,8 +280,8 @@ class LIBARDOUR_API PresentationInfo : public PBD::Stateful
 	static int selection_counter;
 };
 
+LIBARDOUR_API std::ostream& operator<<(std::ostream& o, PresentationInfo const& rid);
+
 }
 
-std::ostream& operator<<(std::ostream& o, ARDOUR::PresentationInfo const& rid);
-
 #endif /* __libardour_presentation_info_h__ */
diff --git a/libs/ardour/ardour/tempo.h b/libs/ardour/ardour/tempo.h
index 69e1af1473..726f4a94e0 100644
--- a/libs/ardour/ardour/tempo.h
+++ b/libs/ardour/ardour/tempo.h
@@ -627,11 +627,11 @@ private:
 	MeterSection* copy_metrics_and_point (const Metrics& metrics, Metrics& copy, MeterSection* section) const;
 };
 
-}; /* namespace ARDOUR */
+LIBARDOUR_API std::ostream& operator<< (std::ostream&, const Meter&);
+LIBARDOUR_API std::ostream& operator<< (std::ostream&, const Tempo&);
+LIBARDOUR_API std::ostream& operator<< (std::ostream&, const MetricSection&);
 
-LIBARDOUR_API std::ostream& operator<< (std::ostream&, const ARDOUR::Meter&);
-LIBARDOUR_API std::ostream& operator<< (std::ostream&, const ARDOUR::Tempo&);
-LIBARDOUR_API std::ostream& operator<< (std::ostream&, const ARDOUR::MetricSection&);
+}; /* namespace ARDOUR */
 
 namespace PBD {
 	DEFINE_ENUM_CONVERT (ARDOUR::TempoSection::Type)
diff --git a/libs/ardour/chan_count.cc b/libs/ardour/chan_count.cc
index 6324f8c0fb..1ee567fc3e 100644
--- a/libs/ardour/chan_count.cc
+++ b/libs/ardour/chan_count.cc
@@ -66,8 +66,9 @@ ChanCount::state(const std::string& name) const
 // Statics
 const ChanCount ChanCount::ZERO     = ChanCount();
 
-} // namespace ARDOUR
-
-std::ostream& operator<<(std::ostream& o, const ARDOUR::ChanCount& c) {
+std::ostream& operator<<(std::ostream& o, const ChanCount& c) {
 	return o << "AUDIO=" << c.n_audio() << ":MIDI=" << c.n_midi();
 }
+
+} // namespace ARDOUR
+
diff --git a/libs/ardour/chan_mapping.cc b/libs/ardour/chan_mapping.cc
index d907efe732..02817fcb62 100644
--- a/libs/ardour/chan_mapping.cc
+++ b/libs/ardour/chan_mapping.cc
@@ -257,16 +257,12 @@ ChanMapping::count () const
 	return rv;
 }
 
-
-
-} // namespace ARDOUR
-
-std::ostream& operator<<(std::ostream& o, const ARDOUR::ChanMapping& cm)
+std::ostream& operator<<(std::ostream& o, const ChanMapping& cm)
 {
-	const ARDOUR::ChanMapping::Mappings& mp (cm.mappings());
-	for (ARDOUR::ChanMapping::Mappings::const_iterator tm = mp.begin(); tm != mp.end(); ++tm) {
+	const ChanMapping::Mappings& mp (cm.mappings());
+	for (ChanMapping::Mappings::const_iterator tm = mp.begin(); tm != mp.end(); ++tm) {
 		o << tm->first.to_string() << endl;
-		for (ARDOUR::ChanMapping::TypeMapping::const_iterator i = tm->second.begin();
+		for (ChanMapping::TypeMapping::const_iterator i = tm->second.begin();
 				i != tm->second.end(); ++i) {
 			o << "\t" << i->first << " => " << i->second << endl;
 		}
@@ -274,3 +270,5 @@ std::ostream& operator<<(std::ostream& o, const ARDOUR::ChanMapping& cm)
 
 	return o;
 }
+
+} // namespace ARDOUR
diff --git a/libs/ardour/ltc_slave.cc b/libs/ardour/ltc_slave.cc
index 6a2f71dacb..b9f4c25459 100644
--- a/libs/ardour/ltc_slave.cc
+++ b/libs/ardour/ltc_slave.cc
@@ -264,6 +264,7 @@ LTC_TransportMaster::equal_ltc_sample_time(LTCFrame *a, LTCFrame *b) {
 	}
 	return true;
 }
+
 static ostream& operator<< (ostream& ostr, LTCFrame& a)
 {
 	ostr
diff --git a/libs/ardour/plugin_insert.cc b/libs/ardour/plugin_insert.cc
index b0048bbd01..2470ce9094 100644
--- a/libs/ardour/plugin_insert.cc
+++ b/libs/ardour/plugin_insert.cc
@@ -3382,7 +3382,7 @@ PluginInsert::clear_stats ()
 	g_atomic_int_set (&_stat_reset, 1);
 }
 
-std::ostream& operator<<(std::ostream& o, const ARDOUR::PluginInsert::Match& m)
+std::ostream& ARDOUR::operator<<(std::ostream& o, const ARDOUR::PluginInsert::Match& m)
 {
 	switch (m.method) {
 		case PluginInsert::Impossible: o << "Impossible"; break;
diff --git a/libs/ardour/presentation_info.cc b/libs/ardour/presentation_info.cc
index 52cbaa39df..db34179f2a 100644
--- a/libs/ardour/presentation_info.cc
+++ b/libs/ardour/presentation_info.cc
@@ -297,7 +297,7 @@ PresentationInfo::operator= (PresentationInfo const& other)
 }
 
 std::ostream&
-operator<<(std::ostream& o, ARDOUR::PresentationInfo const& pi)
+ARDOUR::operator<<(std::ostream& o, ARDOUR::PresentationInfo const& pi)
 {
 	return o << pi.order() << '/' << enum_2_string (pi.flags()) << '/' << pi.color();
 }
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 60d4583c73..c9fb5657ef 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -3230,17 +3230,11 @@ Session::add_routes_inner (RouteList& new_routes, bool input_auto_connect, bool
 				}
 			}
 
-#if !defined(__APPLE__) && !defined(__FreeBSD__)
-			/* 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) {
 				auto_connect_route (r, input_auto_connect, output_auto_connect, ChanCount (), ChanCount (), existing_inputs, existing_outputs);
diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index 38e3ecc9b5..a164cf2c93 100644
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -4943,17 +4943,17 @@ struct bbtcmp {
 };
 
 std::ostream&
-operator<< (std::ostream& o, const Meter& m) {
+ARDOUR::operator<< (std::ostream& o, const ARDOUR::Meter& m) {
 	return o << m.divisions_per_bar() << '/' << m.note_divisor();
 }
 
 std::ostream&
-operator<< (std::ostream& o, const Tempo& t) {
+ARDOUR::operator<< (std::ostream& o, const ARDOUR::Tempo& t) {
 	return o << t.note_types_per_minute() << " 1/" << t.note_type() << "'s per minute";
 }
 
 std::ostream&
-operator<< (std::ostream& o, const MetricSection& section) {
+ARDOUR::operator<< (std::ostream& o, const ARDOUR::MetricSection& section) {
 
 	o << "MetricSection @ " << section.sample() << ' ';
 
diff --git a/libs/canvas/canvas/canvas.h b/libs/canvas/canvas/canvas.h
index 90b6db4192..ba87c262f6 100644
--- a/libs/canvas/canvas/canvas.h
+++ b/libs/canvas/canvas/canvas.h
@@ -323,8 +323,8 @@ private:
 	void scrolled ();
 };
 
+std::ostream& operator<< (std::ostream&, const Canvas&);
+
 }
 
-std::ostream& operator<< (std::ostream&, const ArdourCanvas::Canvas&);
-
 #endif
diff --git a/libs/canvas/canvas/item.h b/libs/canvas/canvas/item.h
index 9d9ee62219..0b03dc294e 100644
--- a/libs/canvas/canvas/item.h
+++ b/libs/canvas/canvas/item.h
@@ -333,7 +333,7 @@ private:
 	void propagate_show_hide ();
 };
 
-extern LIBCANVAS_API std::ostream& operator<< (std::ostream&, const ArdourCanvas::Item&);
+extern LIBCANVAS_API std::ostream& operator<< (std::ostream&, const Item&);
 
 }
 
diff --git a/libs/evoral/ControlSet.cc b/libs/evoral/ControlSet.cc
index c9096187db..82b841dca8 100644
--- a/libs/evoral/ControlSet.cc
+++ b/libs/evoral/ControlSet.cc
@@ -104,12 +104,11 @@ ControlSet::clear_controls ()
 	}
 }
 
-} // namespace Evoral
-
-/* No good place for this so just put it here */
-
 std::ostream&
-std::operator<< (std::ostream & str, Evoral::Parameter const & p)
+operator<< (std::ostream & str, Parameter const & p)
 {
 	return str << p.type() << '-' << p.id() << '-' << (int) p.channel();
 }
+
+} // namespace Evoral
+
diff --git a/libs/evoral/evoral/Parameter.h b/libs/evoral/evoral/Parameter.h
index 672afec653..5af6937c1f 100644
--- a/libs/evoral/evoral/Parameter.h
+++ b/libs/evoral/evoral/Parameter.h
@@ -87,11 +87,9 @@ private:
 	uint8_t       _channel;
 };
 
-} // namespace Evoral
+std::ostream& operator<< (std::ostream &str, Parameter const &);
 
-namespace std {
-std::ostream& operator<< (std::ostream &str, Evoral::Parameter const &);
-}
+} // namespace Evoral
 
 #endif // EVORAL_PARAMETER_HPP
 
diff --git a/libs/evoral/evoral/Sequence.h b/libs/evoral/evoral/Sequence.h
index 04864dde8d..15f09a3fa4 100644
--- a/libs/evoral/evoral/Sequence.h
+++ b/libs/evoral/evoral/Sequence.h
@@ -371,11 +371,9 @@ private:
 	uint8_t _highest_note;
 };
 
+template<typename Time> /*LIBEVORAL_API*/ std::ostream& operator<<(std::ostream& o, const Evoral::Sequence<Time>& s) { s.dump (o); return o; }
 
 } // namespace Evoral
 
-template<typename Time> /*LIBEVORAL_API*/ std::ostream& operator<<(std::ostream& o, const Evoral::Sequence<Time>& s) { s.dump (o); return o; }
-
-
 #endif // EVORAL_SEQUENCE_HPP
 
diff --git a/libs/pbd/id.cc b/libs/pbd/id.cc
index 79bc9cd4de..be264fd1a4 100644
--- a/libs/pbd/id.cc
+++ b/libs/pbd/id.cc
@@ -105,7 +105,7 @@ ID::operator= (const ID& other)
 }
 
 ostream&
-operator<< (ostream& ostr, const ID& id)
+PBD::operator<< (ostream& ostr, const ID& id)
 {
 	ostr << id.to_s();
 	return ostr;
diff --git a/libs/pbd/pbd/id.h b/libs/pbd/pbd/id.h
index 7d2519d6c3..9b6d2a3578 100644
--- a/libs/pbd/pbd/id.h
+++ b/libs/pbd/pbd/id.h
@@ -75,8 +75,8 @@ class LIBPBD_API ID {
 	static uint64_t _counter;
 };
 
+LIBPBD_API std::ostream& operator<< (std::ostream& ostr, const ID&);
+
 }
 
-LIBPBD_API std::ostream& operator<< (std::ostream& ostr, const PBD::ID&);
-
 #endif /* __pbd_id_h__ */
diff --git a/libs/surfaces/mackie/controls.h b/libs/surfaces/mackie/controls.h
index 85608de48f..73820e2ce1 100644
--- a/libs/surfaces/mackie/controls.h
+++ b/libs/surfaces/mackie/controls.h
@@ -88,9 +88,9 @@ public:
 	bool _in_use;
 };
 
-}
-}
-
 std::ostream & operator<< (std::ostream & os, const ArdourSurface::Mackie::Control & control);
 
+}
+}
+
 #endif /* __mackie_controls_h__ */
diff --git a/libs/surfaces/mackie/device_info.h b/libs/surfaces/mackie/device_info.h
index db0837f26c..1d32c26ead 100644
--- a/libs/surfaces/mackie/device_info.h
+++ b/libs/surfaces/mackie/device_info.h
@@ -127,10 +127,9 @@ class DeviceInfo
 	void shared_buttons ();
 };
 
+std::ostream& operator<< (std::ostream& os, const ArdourSurface::Mackie::DeviceInfo& di);
 
 } // Mackie namespace
 } // ArdourSurface namespace
 
-std::ostream& operator<< (std::ostream& os, const ArdourSurface::Mackie::DeviceInfo& di);
-
 #endif /* __ardour_mackie_control_protocol_device_info_h__ */
diff --git a/libs/surfaces/us2400/controls.h b/libs/surfaces/us2400/controls.h
index 1b3d602eb8..4568af5c25 100644
--- a/libs/surfaces/us2400/controls.h
+++ b/libs/surfaces/us2400/controls.h
@@ -88,9 +88,9 @@ public:
 	bool _in_use;
 };
 
-}
-}
-
 std::ostream & operator<< (std::ostream & os, const ArdourSurface::US2400::Control & control);
 
+}
+}
+
 #endif /* __us2400_controls_h__ */
diff --git a/libs/surfaces/us2400/device_info.h b/libs/surfaces/us2400/device_info.h
index 00aa38cf8a..88c0d30bd0 100644
--- a/libs/surfaces/us2400/device_info.h
+++ b/libs/surfaces/us2400/device_info.h
@@ -122,10 +122,9 @@ class DeviceInfo
 	void shared_buttons ();
 };
 
+std::ostream& operator<< (std::ostream& os, const ArdourSurface::US2400::DeviceInfo& di);
 
 } // US2400 namespace
 } // ArdourSurface namespace
 
-std::ostream& operator<< (std::ostream& os, const ArdourSurface::US2400::DeviceInfo& di);
-
 #endif /* __ardour_us2400_control_protocol_device_info_h__ */
diff --git a/libs/temporal/temporal/bbt_time.h b/libs/temporal/temporal/bbt_time.h
index 5f8f012c27..996daa27ae 100644
--- a/libs/temporal/temporal/bbt_time.h
+++ b/libs/temporal/temporal/bbt_time.h
@@ -112,24 +112,22 @@ struct LIBTEMPORAL_API BBT_Offset
 	BBT_Offset (double beats);
 };
 
-}
-
 inline std::ostream&
-operator<< (std::ostream& o, const Timecode::BBT_Time& bbt)
+operator<< (std::ostream& o, const BBT_Time& bbt)
 {
 	o << bbt.bars << '|' << bbt.beats << '|' << bbt.ticks;
 	return o;
 }
 
 inline std::ostream&
-operator<< (std::ostream& o, const Timecode::BBT_Offset& bbt)
+operator<< (std::ostream& o, const BBT_Offset& bbt)
 {
 	o << bbt.bars << '|' << bbt.beats << '|' << bbt.ticks;
 	return o;
 }
 
 inline std::ostream&
-print_padded (std::ostream& o, const Timecode::BBT_Time& bbt)
+print_padded (std::ostream& o, const BBT_Time& bbt)
 {
 	o << std::setfill ('0') << std::right
 	  << std::setw (3) << bbt.bars << "|"
@@ -139,4 +137,6 @@ print_padded (std::ostream& o, const Timecode::BBT_Time& bbt)
 	return o;
 }
 
+}
+
 #endif /* __timecode_bbt_time_h__ */
diff --git a/libs/temporal/temporal/time.h b/libs/temporal/temporal/time.h
index e527965d99..f66530f003 100644
--- a/libs/temporal/temporal/time.h
+++ b/libs/temporal/temporal/time.h
@@ -162,8 +162,8 @@ sample_to_timecode (
     uint32_t subframes_per_frame,
     bool offset_is_negative, int64_t offset_samples);
 
+extern LIBTEMPORAL_API std::ostream& operator<< (std::ostream& ostr, const Time& t);
+
 } // namespace Timecode
 
-extern LIBTEMPORAL_API std::ostream& operator<< (std::ostream& ostr, const Timecode::Time& t);
-
 #endif // __timecode_time_h__
diff --git a/libs/temporal/time.cc b/libs/temporal/time.cc
index 5de23f342d..19db936ac1 100644
--- a/libs/temporal/time.cc
+++ b/libs/temporal/time.cc
@@ -844,10 +844,11 @@ sample_to_timecode (
 	timecode.drop = timecode_drop_frames;
 }
 
-} // namespace Timecode
-
 std::ostream&
-operator<<(std::ostream& ostr, const Timecode::Time& t)
+operator<<(std::ostream& ostr, const Time& t)
 {
 	return t.print (ostr);
 }
+
+} // namespace Timecode
+
diff --git a/nutemp/t.h b/nutemp/t.h
index d18775fccb..1c0c8c91b8 100644
--- a/nutemp/t.h
+++ b/nutemp/t.h
@@ -420,10 +420,10 @@ class LIBARDOUR_API TempoMap
 	void dump_locked (std::ostream&);
 };
 
+std::ostream& operator<<(std::ostream&, TempoMapPoint const &);
+std::ostream& operator<<(std::ostream&, Tempo const &);
+std::ostream& operator<<(std::ostream&, Meter const &);
+
 }
 
-std::ostream& operator<<(std::ostream&, ARDOUR::TempoMapPoint const &);
-std::ostream& operator<<(std::ostream&, ARDOUR::Tempo const &);
-std::ostream& operator<<(std::ostream&, ARDOUR::Meter const &);
-
 #endif /* __ardour_tempo_h__ */