diff --git a/src/hb.hh b/src/hb.hh
index 203267e83..274a0e98d 100644
--- a/src/hb.hh
+++ b/src/hb.hh
@@ -107,6 +107,7 @@
 #pragma GCC diagnostic warning "-Wmaybe-uninitialized"
 #pragma GCC diagnostic warning "-Wmissing-format-attribute"
 #pragma GCC diagnostic warning "-Wundef"
+#pragma GCC diagnostic warning "-Wunused-but-set-variable"
 #endif
 
 /* Ignored currently, but should be fixed at some point. */