diff --git a/backend/drm/backend.c b/backend/drm/backend.c
index 5a545b192..c2806152b 100644
--- a/backend/drm/backend.c
+++ b/backend/drm/backend.c
@@ -95,7 +95,7 @@ static const struct wlr_backend_impl backend_impl = {
 	.commit = backend_commit,
 };
 
-bool wlr_backend_is_drm(struct wlr_backend *b) {
+bool wlr_backend_is_drm(const struct wlr_backend *b) {
 	return b->impl == &backend_impl;
 }
 
diff --git a/backend/drm/drm.c b/backend/drm/drm.c
index fe9dcc341..6c37ab668 100644
--- a/backend/drm/drm.c
+++ b/backend/drm/drm.c
@@ -1299,7 +1299,7 @@ static const struct wlr_output_impl output_impl = {
 	.get_primary_formats = drm_connector_get_primary_formats,
 };
 
-bool wlr_output_is_drm(struct wlr_output *output) {
+bool wlr_output_is_drm(const struct wlr_output *output) {
 	return output->impl == &output_impl;
 }
 
diff --git a/backend/headless/backend.c b/backend/headless/backend.c
index d03f520b8..0f21b53f4 100644
--- a/backend/headless/backend.c
+++ b/backend/headless/backend.c
@@ -81,6 +81,6 @@ struct wlr_backend *wlr_headless_backend_create(struct wl_event_loop *loop) {
 	return &backend->backend;
 }
 
-bool wlr_backend_is_headless(struct wlr_backend *backend) {
+bool wlr_backend_is_headless(const struct wlr_backend *backend) {
 	return backend->impl == &backend_impl;
 }
diff --git a/backend/headless/output.c b/backend/headless/output.c
index a4cdb17c3..0464e0d1b 100644
--- a/backend/headless/output.c
+++ b/backend/headless/output.c
@@ -106,7 +106,7 @@ static const struct wlr_output_impl output_impl = {
 	.move_cursor = output_move_cursor,
 };
 
-bool wlr_output_is_headless(struct wlr_output *wlr_output) {
+bool wlr_output_is_headless(const struct wlr_output *wlr_output) {
 	return wlr_output->impl == &output_impl;
 }
 
diff --git a/backend/libinput/backend.c b/backend/libinput/backend.c
index 121731b31..0c72c6849 100644
--- a/backend/libinput/backend.c
+++ b/backend/libinput/backend.c
@@ -155,7 +155,7 @@ static const struct wlr_backend_impl backend_impl = {
 	.destroy = backend_destroy,
 };
 
-bool wlr_backend_is_libinput(struct wlr_backend *b) {
+bool wlr_backend_is_libinput(const struct wlr_backend *b) {
 	return b->impl == &backend_impl;
 }
 
diff --git a/backend/multi/backend.c b/backend/multi/backend.c
index 3d8fb96f5..3a9aca7e6 100644
--- a/backend/multi/backend.c
+++ b/backend/multi/backend.c
@@ -173,7 +173,7 @@ struct wlr_backend *wlr_multi_backend_create(struct wl_event_loop *loop) {
 	return &backend->backend;
 }
 
-bool wlr_backend_is_multi(struct wlr_backend *b) {
+bool wlr_backend_is_multi(const struct wlr_backend *b) {
 	return b->impl == &backend_impl;
 }
 
diff --git a/backend/wayland/backend.c b/backend/wayland/backend.c
index 14a783b67..0d294b543 100644
--- a/backend/wayland/backend.c
+++ b/backend/wayland/backend.c
@@ -577,7 +577,7 @@ static const struct wlr_backend_impl backend_impl = {
 	.get_drm_fd = backend_get_drm_fd,
 };
 
-bool wlr_backend_is_wl(struct wlr_backend *b) {
+bool wlr_backend_is_wl(const struct wlr_backend *b) {
 	return b->impl == &backend_impl;
 }
 
diff --git a/backend/wayland/output.c b/backend/wayland/output.c
index fb4d1f914..c3442f411 100644
--- a/backend/wayland/output.c
+++ b/backend/wayland/output.c
@@ -1027,7 +1027,7 @@ static const struct wlr_output_impl output_impl = {
 	.get_primary_formats = output_get_formats,
 };
 
-bool wlr_output_is_wl(struct wlr_output *wlr_output) {
+bool wlr_output_is_wl(const struct wlr_output *wlr_output) {
 	return wlr_output->impl == &output_impl;
 }
 
diff --git a/backend/x11/backend.c b/backend/x11/backend.c
index 0983bad0a..20118016d 100644
--- a/backend/x11/backend.c
+++ b/backend/x11/backend.c
@@ -218,7 +218,7 @@ static const struct wlr_backend_impl backend_impl = {
 	.get_drm_fd = backend_get_drm_fd,
 };
 
-bool wlr_backend_is_x11(struct wlr_backend *backend) {
+bool wlr_backend_is_x11(const struct wlr_backend *backend) {
 	return backend->impl == &backend_impl;
 }
 
diff --git a/backend/x11/output.c b/backend/x11/output.c
index 51a9c1441..40e601f0b 100644
--- a/backend/x11/output.c
+++ b/backend/x11/output.c
@@ -711,7 +711,7 @@ void handle_x11_configure_notify(struct wlr_x11_output *output,
 	wlr_output_state_finish(&state);
 }
 
-bool wlr_output_is_x11(struct wlr_output *wlr_output) {
+bool wlr_output_is_x11(const struct wlr_output *wlr_output) {
 	return wlr_output->impl == &output_impl;
 }
 
diff --git a/include/wlr/backend/drm.h b/include/wlr/backend/drm.h
index 3ca6390ab..233bbcb74 100644
--- a/include/wlr/backend/drm.h
+++ b/include/wlr/backend/drm.h
@@ -39,8 +39,8 @@ struct wlr_drm_lease {
 struct wlr_backend *wlr_drm_backend_create(struct wlr_session *session,
 	struct wlr_device *dev, struct wlr_backend *parent);
 
-bool wlr_backend_is_drm(struct wlr_backend *backend);
-bool wlr_output_is_drm(struct wlr_output *output);
+bool wlr_backend_is_drm(const struct wlr_backend *backend);
+bool wlr_output_is_drm(const struct wlr_output *output);
 
 /**
  * Get the parent DRM backend, if any.
diff --git a/include/wlr/backend/headless.h b/include/wlr/backend/headless.h
index 126f1ff21..5487c6085 100644
--- a/include/wlr/backend/headless.h
+++ b/include/wlr/backend/headless.h
@@ -25,7 +25,7 @@ struct wlr_backend *wlr_headless_backend_create(struct wl_event_loop *loop);
 struct wlr_output *wlr_headless_add_output(struct wlr_backend *backend,
 	unsigned int width, unsigned int height);
 
-bool wlr_backend_is_headless(struct wlr_backend *backend);
-bool wlr_output_is_headless(struct wlr_output *output);
+bool wlr_backend_is_headless(const struct wlr_backend *backend);
+bool wlr_output_is_headless(const struct wlr_output *output);
 
 #endif
diff --git a/include/wlr/backend/libinput.h b/include/wlr/backend/libinput.h
index 2a4e1996e..cb5ef824d 100644
--- a/include/wlr/backend/libinput.h
+++ b/include/wlr/backend/libinput.h
@@ -29,7 +29,7 @@ struct libinput_device *wlr_libinput_get_device_handle(
 struct libinput_tablet_tool *wlr_libinput_get_tablet_tool_handle(
 		struct wlr_tablet_tool *wlr_tablet_tool);
 
-bool wlr_backend_is_libinput(struct wlr_backend *backend);
+bool wlr_backend_is_libinput(const struct wlr_backend *backend);
 bool wlr_input_device_is_libinput(struct wlr_input_device *device);
 
 #endif
diff --git a/include/wlr/backend/multi.h b/include/wlr/backend/multi.h
index c4322d98b..cc3e41b4e 100644
--- a/include/wlr/backend/multi.h
+++ b/include/wlr/backend/multi.h
@@ -26,7 +26,7 @@ bool wlr_multi_backend_add(struct wlr_backend *multi,
 void wlr_multi_backend_remove(struct wlr_backend *multi,
 	struct wlr_backend *backend);
 
-bool wlr_backend_is_multi(struct wlr_backend *backend);
+bool wlr_backend_is_multi(const struct wlr_backend *backend);
 bool wlr_multi_is_empty(struct wlr_backend *backend);
 
 void wlr_multi_for_each_backend(struct wlr_backend *backend,
diff --git a/include/wlr/backend/wayland.h b/include/wlr/backend/wayland.h
index c732de68c..7a41b3d09 100644
--- a/include/wlr/backend/wayland.h
+++ b/include/wlr/backend/wayland.h
@@ -46,7 +46,7 @@ struct wlr_output *wlr_wl_output_create_from_surface(struct wlr_backend *backend
 /**
  * Check whether the provided backend is a Wayland backend.
  */
-bool wlr_backend_is_wl(struct wlr_backend *backend);
+bool wlr_backend_is_wl(const struct wlr_backend *backend);
 
 /**
  * Check whether the provided input device is a Wayland input device.
@@ -56,7 +56,7 @@ bool wlr_input_device_is_wl(struct wlr_input_device *device);
 /**
  * Check whether the provided output device is a Wayland output device.
  */
-bool wlr_output_is_wl(struct wlr_output *output);
+bool wlr_output_is_wl(const struct wlr_output *output);
 
 /**
  * Sets the title of a struct wlr_output which is a Wayland toplevel.
diff --git a/include/wlr/backend/x11.h b/include/wlr/backend/x11.h
index 1791041ce..8e8bc9870 100644
--- a/include/wlr/backend/x11.h
+++ b/include/wlr/backend/x11.h
@@ -31,7 +31,7 @@ struct wlr_output *wlr_x11_output_create(struct wlr_backend *backend);
 /**
  * Check whether this backend is an X11 backend.
  */
-bool wlr_backend_is_x11(struct wlr_backend *backend);
+bool wlr_backend_is_x11(const struct wlr_backend *backend);
 
 /**
  * Check whether this input device is an X11 input device.
@@ -41,7 +41,7 @@ bool wlr_input_device_is_x11(struct wlr_input_device *device);
 /**
  * Check whether this output device is an X11 output device.
  */
-bool wlr_output_is_x11(struct wlr_output *output);
+bool wlr_output_is_x11(const struct wlr_output *output);
 
 /**
  * Sets the title of a struct wlr_output which is an X11 window.
diff --git a/include/wlr/render/gles2.h b/include/wlr/render/gles2.h
index 454e7eb0e..87a57fa54 100644
--- a/include/wlr/render/gles2.h
+++ b/include/wlr/render/gles2.h
@@ -42,9 +42,9 @@ struct wlr_gles2_texture_attribs {
 	bool has_alpha;
 };
 
-bool wlr_renderer_is_gles2(struct wlr_renderer *wlr_renderer);
-bool wlr_render_timer_is_gles2(struct wlr_render_timer *timer);
-bool wlr_texture_is_gles2(struct wlr_texture *texture);
+bool wlr_renderer_is_gles2(const struct wlr_renderer *wlr_renderer);
+bool wlr_render_timer_is_gles2(const struct wlr_render_timer *timer);
+bool wlr_texture_is_gles2(const struct wlr_texture *texture);
 void wlr_gles2_texture_get_attribs(struct wlr_texture *texture,
 	struct wlr_gles2_texture_attribs *attribs);
 
diff --git a/include/wlr/render/pixman.h b/include/wlr/render/pixman.h
index 206dd78c6..2951f5e9e 100644
--- a/include/wlr/render/pixman.h
+++ b/include/wlr/render/pixman.h
@@ -14,8 +14,8 @@
 
 struct wlr_renderer *wlr_pixman_renderer_create(void);
 
-bool wlr_renderer_is_pixman(struct wlr_renderer *wlr_renderer);
-bool wlr_texture_is_pixman(struct wlr_texture *texture);
+bool wlr_renderer_is_pixman(const struct wlr_renderer *wlr_renderer);
+bool wlr_texture_is_pixman(const struct wlr_texture *texture);
 
 pixman_image_t *wlr_pixman_renderer_get_buffer_image(
     struct wlr_renderer *wlr_renderer, struct wlr_buffer *wlr_buffer);
diff --git a/include/wlr/render/vulkan.h b/include/wlr/render/vulkan.h
index 50f8c558d..170665dd0 100644
--- a/include/wlr/render/vulkan.h
+++ b/include/wlr/render/vulkan.h
@@ -25,8 +25,8 @@ VkPhysicalDevice wlr_vk_renderer_get_physical_device(struct wlr_renderer *render
 VkDevice wlr_vk_renderer_get_device(struct wlr_renderer *renderer);
 uint32_t wlr_vk_renderer_get_queue_family(struct wlr_renderer *renderer);
 
-bool wlr_renderer_is_vk(struct wlr_renderer *wlr_renderer);
-bool wlr_texture_is_vk(struct wlr_texture *texture);
+bool wlr_renderer_is_vk(const struct wlr_renderer *wlr_renderer);
+bool wlr_texture_is_vk(const struct wlr_texture *texture);
 
 void wlr_vk_texture_get_image_attribs(struct wlr_texture *texture,
 	struct wlr_vk_image_attribs *attribs);
diff --git a/include/xwayland/selection.h b/include/xwayland/selection.h
index 308310232..2f333f8e0 100644
--- a/include/xwayland/selection.h
+++ b/include/xwayland/selection.h
@@ -82,9 +82,9 @@ void xwm_handle_selection_notify(struct wlr_xwm *xwm,
 	xcb_selection_notify_event_t *event);
 int xwm_handle_xfixes_selection_notify(struct wlr_xwm *xwm,
 	xcb_xfixes_selection_notify_event_t *event);
-bool data_source_is_xwayland(struct wlr_data_source *wlr_source);
+bool data_source_is_xwayland(const struct wlr_data_source *wlr_source);
 bool primary_selection_source_is_xwayland(
-	struct wlr_primary_selection_source *wlr_source);
+	const struct wlr_primary_selection_source *wlr_source);
 
 void xwm_seat_handle_start_drag(struct wlr_xwm *xwm, struct wlr_drag *drag);
 
diff --git a/render/gles2/renderer.c b/render/gles2/renderer.c
index e362daee8..7f01b8acd 100644
--- a/render/gles2/renderer.c
+++ b/render/gles2/renderer.c
@@ -29,7 +29,7 @@
 static const struct wlr_renderer_impl renderer_impl;
 static const struct wlr_render_timer_impl render_timer_impl;
 
-bool wlr_renderer_is_gles2(struct wlr_renderer *wlr_renderer) {
+bool wlr_renderer_is_gles2(const struct wlr_renderer *wlr_renderer) {
 	return wlr_renderer->impl == &renderer_impl;
 }
 
@@ -40,7 +40,7 @@ struct wlr_gles2_renderer *gles2_get_renderer(
 	return renderer;
 }
 
-bool wlr_render_timer_is_gles2(struct wlr_render_timer *timer) {
+bool wlr_render_timer_is_gles2(const struct wlr_render_timer *timer) {
 	return timer->impl == &render_timer_impl;
 }
 
diff --git a/render/gles2/texture.c b/render/gles2/texture.c
index 9a967ebdb..7460755cd 100644
--- a/render/gles2/texture.c
+++ b/render/gles2/texture.c
@@ -16,7 +16,7 @@
 
 static const struct wlr_texture_impl texture_impl;
 
-bool wlr_texture_is_gles2(struct wlr_texture *wlr_texture) {
+bool wlr_texture_is_gles2(const struct wlr_texture *wlr_texture) {
 	return wlr_texture->impl == &texture_impl;
 }
 
diff --git a/render/pixman/renderer.c b/render/pixman/renderer.c
index 4631a33ab..25c558a9d 100644
--- a/render/pixman/renderer.c
+++ b/render/pixman/renderer.c
@@ -12,7 +12,7 @@
 
 static const struct wlr_renderer_impl renderer_impl;
 
-bool wlr_renderer_is_pixman(struct wlr_renderer *wlr_renderer) {
+bool wlr_renderer_is_pixman(const struct wlr_renderer *wlr_renderer) {
 	return wlr_renderer->impl == &renderer_impl;
 }
 
@@ -69,7 +69,7 @@ static struct wlr_pixman_buffer *get_buffer(
 
 static const struct wlr_texture_impl texture_impl;
 
-bool wlr_texture_is_pixman(struct wlr_texture *texture) {
+bool wlr_texture_is_pixman(const struct wlr_texture *texture) {
 	return texture->impl == &texture_impl;
 }
 
diff --git a/render/vulkan/renderer.c b/render/vulkan/renderer.c
index da17a4703..68c5e96eb 100644
--- a/render/vulkan/renderer.c
+++ b/render/vulkan/renderer.c
@@ -46,7 +46,7 @@ static bool default_debug = true;
 
 static const struct wlr_renderer_impl renderer_impl;
 
-bool wlr_renderer_is_vk(struct wlr_renderer *wlr_renderer) {
+bool wlr_renderer_is_vk(const struct wlr_renderer *wlr_renderer) {
 	return wlr_renderer->impl == &renderer_impl;
 }
 
diff --git a/render/vulkan/texture.c b/render/vulkan/texture.c
index 57db97a56..452d787da 100644
--- a/render/vulkan/texture.c
+++ b/render/vulkan/texture.c
@@ -15,7 +15,7 @@
 
 static const struct wlr_texture_impl texture_impl;
 
-bool wlr_texture_is_vk(struct wlr_texture *wlr_texture) {
+bool wlr_texture_is_vk(const struct wlr_texture *wlr_texture) {
 	return wlr_texture->impl == &texture_impl;
 }
 
diff --git a/xwayland/selection/incoming.c b/xwayland/selection/incoming.c
index 85d7775cd..4fa851b2f 100644
--- a/xwayland/selection/incoming.c
+++ b/xwayland/selection/incoming.c
@@ -249,7 +249,7 @@ struct x11_data_source {
 static const struct wlr_data_source_impl data_source_impl;
 
 bool data_source_is_xwayland(
-		struct wlr_data_source *wlr_source) {
+		const struct wlr_data_source *wlr_source) {
 	return wlr_source->impl == &data_source_impl;
 }
 
@@ -292,7 +292,7 @@ static const struct wlr_primary_selection_source_impl
 	primary_selection_source_impl;
 
 bool primary_selection_source_is_xwayland(
-		struct wlr_primary_selection_source *wlr_source) {
+		const struct wlr_primary_selection_source *wlr_source) {
 	return wlr_source->impl == &primary_selection_source_impl;
 }