diff --git a/libs/ardour/audio_unit.cc b/libs/ardour/audio_unit.cc
index 2c70852c33..1c471eaa22 100644
--- a/libs/ardour/audio_unit.cc
+++ b/libs/ardour/audio_unit.cc
@@ -1813,9 +1813,9 @@ AUPlugin::describe_io_port (ARDOUR::DataType dt, bool input, uint32_t id) const
 	}
 
 	if (input) {
-		ss << " " << _("In") << " ";
+		ss << " " << S_("IO|In") << " ";
 	} else {
-		ss << " " << _("Out") << " ";
+		ss << " " << S_("IO|Out") << " ";
 	}
 
 	ss << (id + 1);
diff --git a/libs/ardour/io.cc b/libs/ardour/io.cc
index 720376404e..7784a8eff5 100644
--- a/libs/ardour/io.cc
+++ b/libs/ardour/io.cc
@@ -1159,7 +1159,7 @@ IO::apply_pretty_name ()
 	for (PortSet::iterator i = _ports.begin (); i != _ports.end(); ++i, ++pn) {
 		(*i)->set_pretty_name (string_compose (("%1/%2 %3"),
 					_pretty_name_prefix,
-					_direction == Output ? _("Out") : _("In"),
+					_direction == Output ? S_("IO|Out") : S_("IO|In"),
 					pn));
 	}
 }
diff --git a/libs/ardour/io_plug.cc b/libs/ardour/io_plug.cc
index 1fccf87b3a..46896b8c5d 100644
--- a/libs/ardour/io_plug.cc
+++ b/libs/ardour/io_plug.cc
@@ -75,7 +75,7 @@ IOPlug::~IOPlug ()
 std::string
 IOPlug::io_name (std::string const& n) const
 {
-	return (string_compose ("%1/%2/%3", _("IO"), _pre ? _("Pre"): _("Post"), n.empty () ? name () : n));
+	return (string_compose ("%1/%2/%3", _("IO"), _pre ? S_("IO|Pre"): S_("IO|Post"), n.empty () ? name () : n));
 }
 
 std::string
diff --git a/libs/ardour/plugin.cc b/libs/ardour/plugin.cc
index 4140f6b6bc..52ceb21dc3 100644
--- a/libs/ardour/plugin.cc
+++ b/libs/ardour/plugin.cc
@@ -333,9 +333,9 @@ Plugin::describe_io_port (ARDOUR::DataType dt, bool input, uint32_t id) const
 			break;
 	}
 	if (input) {
-		ss << _("In") << " ";
+		ss << S_("IO|In") << " ";
 	} else {
-		ss << _("Out") << " ";
+		ss << S_("IO|Out") << " ";
 	}
 
 	std::stringstream gn;
diff --git a/libs/surfaces/push2/track_mix.cc b/libs/surfaces/push2/track_mix.cc
index 7ece866185..a1028aa1dc 100644
--- a/libs/surfaces/push2/track_mix.cc
+++ b/libs/surfaces/push2/track_mix.cc
@@ -123,10 +123,10 @@ TrackMixLayout::TrackMixLayout (Push2& p, Session & s, std::string const & name)
 			break;
 		case 3:
 			_upper_text[n]->set (_("Track Trim"));
-			_lower_text[n]->set (_("In"));
+			_lower_text[n]->set (S_("Monitor|In"));
 			break;
 		case 4:
-			_lower_text[n]->set (_("Disk"));
+			_lower_text[n]->set (S_("Monitor|Disk"));
 			break;
 		case 5:
 			_lower_text[n]->set (_("Solo Iso"));