diff --git a/accessible/atk/moz.build b/accessible/atk/moz.build
index 67a59e65365..dae3f86a604 100644
--- a/accessible/atk/moz.build
+++ b/accessible/atk/moz.build
@@ -52,6 +52,7 @@ if CONFIG['MOZ_ENABLE_DBUS']:
 
 include('/ipc/chromium/chromium-config.mozbuild')
 
-if CONFIG['CLANG_CXX']:
-    # Suppress clang warning about unused function from gobject's RTTI macros.
-    CXXFLAGS += ['-Wno-unused-function']
+if CONFIG['CLANG_CXX'] or CONFIG['GNU_CXX']:
+    # Used in G_DEFINE_TYPE_EXTENDED macro, probably fixed in newer glib /
+    # gobject headers. See bug 1243331 comment 3.
+    CXXFLAGS += ['-Wno-unused-local-typedefs']