diff --git a/gobject/meson.build b/gobject/meson.build
index 4bba94c96..91823af79 100644
--- a/gobject/meson.build
+++ b/gobject/meson.build
@@ -147,7 +147,7 @@ libgobject = library('gobject-2.0',
   install : true,
   include_directories : [configinc],
   dependencies : [libffi_dep, libglib_dep],
-  c_args : ['-DG_LOG_DOMAIN="GLib-GObject"', '-DGOBJECT_COMPILATION'],
+  c_args : ['-DG_LOG_DOMAIN="GLib-GObject"', '-DGOBJECT_COMPILATION', warning_sign_conversion_args],
   gnu_symbol_visibility : 'hidden',
   link_args : glib_link_flags,
 )
diff --git a/gobject/tests/meson.build b/gobject/tests/meson.build
index 268dd5dd9..0ae4e86ed 100644
--- a/gobject/tests/meson.build
+++ b/gobject/tests/meson.build
@@ -179,7 +179,7 @@ test_env.set('G_TEST_SRCDIR', meson.current_source_dir())
 test_env.set('G_TEST_BUILDDIR', meson.current_build_dir())
 
 test_deps = [libm, thread_dep, libglib_dep, libgobject_dep]
-test_cargs = ['-DG_LOG_DOMAIN="GLib-GObject"', '-UG_DISABLE_ASSERT']
+test_cargs = ['-DG_LOG_DOMAIN="GLib-GObject"', '-UG_DISABLE_ASSERT', warning_sign_conversion_args]
 test_cpp_args = test_cargs
 
 foreach test_name, extra_args : gobject_tests
diff --git a/meson.build b/meson.build
index b11151d28..48cb6cd3c 100644
--- a/meson.build
+++ b/meson.build
@@ -660,6 +660,13 @@ if have_cxx
   add_project_arguments(cxx.get_supported_arguments(warning_cxx_args), language: 'cpp')
 endif
 
+# FIXME: This is checked and implemented separately from warning_common_args for
+# now because it causes so many warnings. Adding it as a variable in various
+# directories allows us to gradually tighten up support for it. Eventually, the
+# warning can be enabled unconditionally in warning_c_args, and this variable
+# removed. See https://gitlab.gnome.org/GNOME/glib/-/issues/3405
+warning_sign_conversion_args = cc.get_supported_arguments(['-Wsign-conversion'])
+
 # FIXME: We cannot build some of the GResource tests with -z nodelete, which
 # means we cannot use that flag in add_project_link_arguments(), and must add
 # it to the relevant targets manually. We do the same with -Bsymbolic-functions