diff --git a/meson.build b/meson.build
index a8de781..31db00e 100644
--- a/meson.build
+++ b/meson.build
@@ -103,6 +103,7 @@ test_c_args = [
   '-Wno-switch-enum',
   '-Wtype-limits',
   '-Wunused-function',
+  '-Wunused-variable',
   '-DGLIB_VERSION_MIN_REQUIRED=GLIB_VERSION_2_64',
   '-DGLIB_VERSION_MAX_ALLOWED=GLIB_VERSION_2_70',
   # see https://gitlab.gnome.org/GNOME/evolution-data-server/-/issues/332