diff --git a/libs/backends/alsa/alsa_audiobackend.cc b/libs/backends/alsa/alsa_audiobackend.cc
index a3ba3f36c4..ed8254e3e3 100644
--- a/libs/backends/alsa/alsa_audiobackend.cc
+++ b/libs/backends/alsa/alsa_audiobackend.cc
@@ -1289,7 +1289,7 @@ AlsaAudioBackend::get_ports (
 		}
 	}
 
-	for (PortIndex::iterator i = _ports.begin (); i != _ports.end (); ++i) {
+	for (PortIndex::const_iterator i = _ports.begin (); i != _ports.end (); ++i) {
 		AlsaPort* port = *i;
 		if ((port->type () == type) && flags == (port->flags () & flags)) {
 			if (!use_regexp || !regexec (&port_regex, port->name ().c_str (), 0, NULL, 0)) {
@@ -1814,7 +1814,7 @@ AlsaAudioBackend::n_physical_outputs () const
 {
 	int n_midi = 0;
 	int n_audio = 0;
-	for (PortIndex::iterator i = _ports.begin (); i != _ports.end (); ++i) {
+	for (PortIndex::const_iterator i = _ports.begin (); i != _ports.end (); ++i) {
 		AlsaPort* port = *i;
 		if (port->is_output () && port->is_physical ()) {
 			switch (port->type ()) {
@@ -1835,7 +1835,7 @@ AlsaAudioBackend::n_physical_inputs () const
 {
 	int n_midi = 0;
 	int n_audio = 0;
-	for (PortIndex::iterator i = _ports.begin (); i != _ports.end (); ++i) {
+	for (PortIndex::const_iterator i = _ports.begin (); i != _ports.end (); ++i) {
 		AlsaPort* port = *i;
 		if (port->is_input () && port->is_physical ()) {
 			switch (port->type ()) {
diff --git a/libs/backends/coreaudio/coreaudio_backend.cc b/libs/backends/coreaudio/coreaudio_backend.cc
index b1721dd2d5..f87282c995 100644
--- a/libs/backends/coreaudio/coreaudio_backend.cc
+++ b/libs/backends/coreaudio/coreaudio_backend.cc
@@ -981,7 +981,7 @@ CoreAudioBackend::get_ports (
 		}
 	}
 
-	for (PortIndex::iterator i = _ports.begin (); i != _ports.end (); ++i) {
+	for (PortIndex::const_iterator i = _ports.begin (); i != _ports.end (); ++i) {
 		CoreBackendPort* port = *i;
 		if ((port->type () == type) && flags == (port->flags () & flags)) {
 			if (!use_regexp || !regexec (&port_regex, port->name ().c_str (), 0, NULL, 0)) {
@@ -1512,7 +1512,7 @@ CoreAudioBackend::n_physical_outputs () const
 {
 	int n_midi = 0;
 	int n_audio = 0;
-	for (PortIndex::iterator i = _ports.begin (); i != _ports.end (); ++i) {
+	for (PortIndex::const_iterator i = _ports.begin (); i != _ports.end (); ++i) {
 		CoreBackendPort* port = *i;
 		if (port->is_output () && port->is_physical ()) {
 			switch (port->type ()) {
@@ -1533,7 +1533,7 @@ CoreAudioBackend::n_physical_inputs () const
 {
 	int n_midi = 0;
 	int n_audio = 0;
-	for (PortIndex::iterator i = _ports.begin (); i != _ports.end (); ++i) {
+	for (PortIndex::const_iterator i = _ports.begin (); i != _ports.end (); ++i) {
 		CoreBackendPort* port = *i;
 		if (port->is_input () && port->is_physical ()) {
 			switch (port->type ()) {