diff --git a/demo/src/server/liquid_framebuffer/services.cc b/demo/src/server/liquid_framebuffer/services.cc
index aea1565f8..dd2757672 100644
--- a/demo/src/server/liquid_framebuffer/services.cc
+++ b/demo/src/server/liquid_framebuffer/services.cc
@@ -201,7 +201,7 @@ namespace Framebuffer
 
 			void release() { }
 
-			Mode mode()
+			Mode mode() const
 			{
 				return Mode(_window_content->fb_w(), _window_content->fb_h(),
 				            Mode::RGB565);
diff --git a/gems/src/server/d3m/input_service.h b/gems/src/server/d3m/input_service.h
index 989fe5c29..884fe4cc9 100644
--- a/gems/src/server/d3m/input_service.h
+++ b/gems/src/server/d3m/input_service.h
@@ -98,7 +98,7 @@ namespace Input {
 			/**
 			 * Return true if input is pending
 			 */
-			bool input_pending() { return connected() && _client.is_pending(); }
+			bool input_pending() const { return connected() && _client.is_pending(); }
 
 			/**
 			 * Return event buffer
@@ -215,7 +215,7 @@ namespace Input {
 
 			Genode::Dataspace_capability dataspace() { return _ev_ds.cap(); }
 
-			bool is_pending()
+			bool is_pending() const
 			{
 				return _source_registry.any_source_has_pending_input();
 			}
diff --git a/os/include/framebuffer_session/client.h b/os/include/framebuffer_session/client.h
index 8dac8092c..ca4d70d36 100644
--- a/os/include/framebuffer_session/client.h
+++ b/os/include/framebuffer_session/client.h
@@ -29,7 +29,7 @@ namespace Framebuffer {
 
 		void release() { call<Rpc_release>(); }
 
-		Mode mode() { return call<Rpc_mode>(); }
+		Mode mode() const { return call<Rpc_mode>(); }
 
 		void mode_sigh(Genode::Signal_context_capability sigh) {
 			call<Rpc_mode_sigh>(sigh); }
diff --git a/os/include/framebuffer_session/framebuffer_session.h b/os/include/framebuffer_session/framebuffer_session.h
index f19948a88..a5303d2ae 100644
--- a/os/include/framebuffer_session/framebuffer_session.h
+++ b/os/include/framebuffer_session/framebuffer_session.h
@@ -86,7 +86,7 @@ namespace Framebuffer {
 		/**
 		 * Request current display-mode properties
 		 */
-		virtual Mode mode() = 0;
+		virtual Mode mode() const = 0;
 
 		/**
 		 * Register signal handler to be notified on mode changes
diff --git a/os/include/input/component.h b/os/include/input/component.h
index b0e35f902..33a9991ce 100644
--- a/os/include/input/component.h
+++ b/os/include/input/component.h
@@ -76,7 +76,7 @@ namespace Input {
 
 			Genode::Dataspace_capability dataspace() { return _ev_ds.cap(); }
 
-			bool is_pending() { return event_pending(); }
+			bool is_pending() const { return event_pending(); }
 
 			int flush()
 			{
diff --git a/os/include/input_session/client.h b/os/include/input_session/client.h
index c2bfe8d9d..b3ffb53a8 100644
--- a/os/include/input_session/client.h
+++ b/os/include/input_session/client.h
@@ -27,7 +27,7 @@ namespace Input {
 		Genode::Dataspace_capability dataspace() {
 			return call<Rpc_dataspace>(); }
 
-		bool is_pending() {
+		bool is_pending() const {
 			return call<Rpc_is_pending>(); }
 
 		int flush() {
diff --git a/os/include/input_session/input_session.h b/os/include/input_session/input_session.h
index b302d29b5..dab340234 100644
--- a/os/include/input_session/input_session.h
+++ b/os/include/input_session/input_session.h
@@ -36,7 +36,7 @@ namespace Input {
 		 *
 		 * \return  true if new events are available
 		 */
-		virtual bool is_pending() = 0;
+		virtual bool is_pending() const = 0;
 
 		/**
 		 * Flush pending events to event buffer
diff --git a/os/src/drivers/framebuffer/fiasco_ux/main.cc b/os/src/drivers/framebuffer/fiasco_ux/main.cc
index 1fd51945b..476cf4991 100644
--- a/os/src/drivers/framebuffer/fiasco_ux/main.cc
+++ b/os/src/drivers/framebuffer/fiasco_ux/main.cc
@@ -47,7 +47,7 @@ namespace Framebuffer {
 
 			void release() { }
 
-			Mode mode()
+			Mode mode() const
 			{
 				if (scr_mode != 16)
 					return Mode(); /* invalid mode */
diff --git a/os/src/drivers/framebuffer/pl11x/main.cc b/os/src/drivers/framebuffer/pl11x/main.cc
index ecabd96ef..2e7b4726e 100644
--- a/os/src/drivers/framebuffer/pl11x/main.cc
+++ b/os/src/drivers/framebuffer/pl11x/main.cc
@@ -167,7 +167,7 @@ namespace Framebuffer
 
 			void release() { }
 
-			Mode mode() { return Mode(SCR_WIDTH, SCR_HEIGHT, Mode::RGB565); }
+			Mode mode() const { return Mode(SCR_WIDTH, SCR_HEIGHT, Mode::RGB565); }
 
 			void mode_sigh(Genode::Signal_context_capability) { }
 
diff --git a/os/src/drivers/framebuffer/sdl/fb_sdl.cc b/os/src/drivers/framebuffer/sdl/fb_sdl.cc
index 6eb8a42b5..e885a20ac 100644
--- a/os/src/drivers/framebuffer/sdl/fb_sdl.cc
+++ b/os/src/drivers/framebuffer/sdl/fb_sdl.cc
@@ -63,7 +63,7 @@ namespace Framebuffer {
 
 			void release() { }
 
-			Mode mode() { return _mode; }
+			Mode mode() const { return _mode; }
 
 			void mode_sigh(Genode::Signal_context_capability) { }
 
diff --git a/os/src/drivers/framebuffer/vesa/main.cc b/os/src/drivers/framebuffer/vesa/main.cc
index 34392ef64..794d11691 100644
--- a/os/src/drivers/framebuffer/vesa/main.cc
+++ b/os/src/drivers/framebuffer/vesa/main.cc
@@ -152,7 +152,7 @@ namespace Framebuffer {
 
 			void release() { }
 
-			Mode mode()
+			Mode mode() const
 			{
 				return Mode(_scr_width, _scr_height,
 				            _scr_mode == 16 ? Mode::RGB565 : Mode::INVALID);
diff --git a/os/src/drivers/input/dummy/main.cc b/os/src/drivers/input/dummy/main.cc
index ba7c54915..ab880190c 100644
--- a/os/src/drivers/input/dummy/main.cc
+++ b/os/src/drivers/input/dummy/main.cc
@@ -43,7 +43,7 @@ namespace Input {
 
 			Dataspace_capability dataspace() { return ev_ds_cap; }
 
-			bool is_pending() { return 0; }
+			bool is_pending() const { return 0; }
 
 			int flush()
 			{
diff --git a/os/src/drivers/input/fiasco_ux/main.cc b/os/src/drivers/input/fiasco_ux/main.cc
index e31b9e4e3..02efd8b19 100644
--- a/os/src/drivers/input/fiasco_ux/main.cc
+++ b/os/src/drivers/input/fiasco_ux/main.cc
@@ -47,7 +47,7 @@ namespace Input {
 
 			Dataspace_capability dataspace() { return ev_ds_cap; }
 
-			bool is_pending() { return Input_drv::event_pending(); }
+			bool is_pending() const { return Input_drv::event_pending(); }
 
 			int flush()
 			{
diff --git a/os/src/server/loader/input_session_component.cc b/os/src/server/loader/input_session_component.cc
index 94a0483b2..ad92d2df7 100644
--- a/os/src/server/loader/input_session_component.cc
+++ b/os/src/server/loader/input_session_component.cc
@@ -49,7 +49,7 @@ Genode::Dataspace_capability Session_component::dataspace()
 }
 
 
-bool Session_component::is_pending(){ return _isc->is_pending(); }
+bool Session_component::is_pending() const { return _isc->is_pending(); }
 
 
 int Session_component::flush()
diff --git a/os/src/server/loader/input_session_component.h b/os/src/server/loader/input_session_component.h
index f3ce38645..8b0fa2fd7 100644
--- a/os/src/server/loader/input_session_component.h
+++ b/os/src/server/loader/input_session_component.h
@@ -51,7 +51,7 @@ namespace Input {
 			 *****************************/
 
 			Genode::Dataspace_capability dataspace();
-			bool is_pending();
+			bool is_pending() const;
 			int flush();
 	};
 }
diff --git a/os/src/server/nit_fb/main.cc b/os/src/server/nit_fb/main.cc
index 8221d4973..2297d4c1a 100644
--- a/os/src/server/nit_fb/main.cc
+++ b/os/src/server/nit_fb/main.cc
@@ -117,7 +117,7 @@ namespace Input {
 
 			Genode::Dataspace_capability dataspace() { return _to_input_ds; }
 
-			bool is_pending() { return _from_input->is_pending(); }
+			bool is_pending() const { return _from_input->is_pending(); }
 
 			int flush()
 			{
diff --git a/os/src/server/nitpicker/genode/main.cc b/os/src/server/nitpicker/genode/main.cc
index df0a6d2bd..d8bb14e97 100644
--- a/os/src/server/nitpicker/genode/main.cc
+++ b/os/src/server/nitpicker/genode/main.cc
@@ -291,7 +291,7 @@ namespace Input {
 
 			Genode::Dataspace_capability dataspace() { return _ev_ram_ds.cap(); }
 
-			bool is_pending() { return _num_ev > 0; }
+			bool is_pending() const { return _num_ev > 0; }
 
 			int flush()
 			{
@@ -343,7 +343,7 @@ namespace Framebuffer {
 
 			void release() { }
 
-			Mode mode()
+			Mode mode() const
 			{
 				return Mode(_buffer->size().w(), _buffer->size().h(),
 				            _buffer->format());