diff --git a/src/hb-iter.hh b/src/hb-iter.hh
index dcc49ee5d..cf3e1fe9d 100644
--- a/src/hb-iter.hh
+++ b/src/hb-iter.hh
@@ -192,7 +192,7 @@ struct hb_iter_fallback_mixin_t
   /* Termination: Implement __more__(), or __len__() if random-access. */
   bool __more__ () const { return bool (thiz()->len ()); }
   unsigned __len__ () const
-  { iter_t c (*thiz()); unsigned l = 0; while (c) { c++; l++; }; return l; }
+  { iter_t c (*thiz()); unsigned l = 0; while (c) { c++; l++; } return l; }
 
   /* Advancing: Implement __next__(), or __forward__() if random-access. */
   void __next__ () { *thiz() += 1; }
diff --git a/src/hb.hh b/src/hb.hh
index e4c7271bd..47f24af1e 100644
--- a/src/hb.hh
+++ b/src/hb.hh
@@ -67,6 +67,7 @@
 #pragma GCC diagnostic error   "-Wcast-function-type"
 #pragma GCC diagnostic error   "-Wdelete-non-virtual-dtor"
 #pragma GCC diagnostic error   "-Wdouble-promotion"
+#pragma GCC diagnostic error   "-Wextra-semi-stmt"
 #pragma GCC diagnostic error   "-Wformat-security"
 #pragma GCC diagnostic error   "-Wimplicit-function-declaration"
 #pragma GCC diagnostic error   "-Winit-self"