diff --git a/kiwmi/output.c b/kiwmi/output.c
index bc9b5a7..0e8a3d4 100644
--- a/kiwmi/output.c
+++ b/kiwmi/output.c
@@ -58,7 +58,7 @@ output_frame_notify(struct wl_listener *listener, void *data)
 }
 
 static void
-output_destroy_nofity(struct wl_listener *listener, void *data)
+output_destroy_nofity(struct wl_listener *listener, void *UNUSED(data))
 {
     struct kiwmi_output *output = wl_container_of(listener, output, destroy);
 
diff --git a/meson.build b/meson.build
index 9d2f6ad..a3b3e08 100644
--- a/meson.build
+++ b/meson.build
@@ -36,4 +36,11 @@ else
 endif
 add_project_arguments('-DKIWMI_VERSION=@0@'.format(version), language: 'c')
 
+compiler = meson.get_compiler('c')
+if compiler.get_id() == 'gcc' or compiler.get_id() == 'clang'
+    add_project_arguments('-DUNUSED(x)=UNUSED_ ## x __attribute__((__unused__))', language: 'c')
+else
+    add_project_arguments('-DUNUSED(x)=UNUSED_ ## x', language: 'c')
+endif
+
 subdir('kiwmi')