diff --git a/libs/backends/portaudio/portaudio_io.cc b/libs/backends/portaudio/portaudio_io.cc
index c4711e06b2..d335c922df 100644
--- a/libs/backends/portaudio/portaudio_io.cc
+++ b/libs/backends/portaudio/portaudio_io.cc
@@ -407,7 +407,7 @@ PortAudioIO::get_host_api_index_from_name (const std::string& name)
 }
 
 PaDeviceIndex
-PortAudioIO::get_default_input_device ()
+PortAudioIO::get_default_input_device () const
 {
 	const PaHostApiInfo* info = Pa_GetHostApiInfo (_host_api_index);
 	if (info == NULL) return -1;
@@ -415,7 +415,7 @@ PortAudioIO::get_default_input_device ()
 }
 
 PaDeviceIndex
-PortAudioIO::get_default_output_device ()
+PortAudioIO::get_default_output_device () const
 {
 	const PaHostApiInfo* info = Pa_GetHostApiInfo (_host_api_index);
 	if (info == NULL) return -1;
diff --git a/libs/backends/portaudio/portaudio_io.h b/libs/backends/portaudio/portaudio_io.h
index 769eb5d096..3b656fd06b 100644
--- a/libs/backends/portaudio/portaudio_io.h
+++ b/libs/backends/portaudio/portaudio_io.h
@@ -50,8 +50,8 @@ public:
 	PaHostApiTypeId get_current_host_api_type () const;
 	PaHostApiIndex get_host_api_index_from_name (const std::string& name);
 
-	PaDeviceIndex get_default_input_device ();
-	PaDeviceIndex get_default_output_device ();
+	PaDeviceIndex get_default_input_device () const;
+	PaDeviceIndex get_default_output_device () const;
 
 	void     discover();
 	void     input_device_list (std::map<int, std::string> &devices) const;