diff --git a/src/hb-face.cc b/src/hb-face.cc
index 724f54d53af4673ad380eb222825c37baea3b06a..a1ae1d7712912a180d0689f826594ebca31fa752 100644
--- a/src/hb-face.cc
+++ b/src/hb-face.cc
@@ -647,8 +647,8 @@ _hb_face_builder_data_reference_blob (hb_face_builder_data_t *data)
   bool is_cff = data->tables.lsearch (HB_TAG ('C','F','F',' ')) || data->tables.lsearch (HB_TAG ('C','F','F','2'));
   hb_tag_t sfnt_tag = is_cff ? OT::OpenTypeFontFile::CFFTag : OT::OpenTypeFontFile::TrueTypeTag;
 
-  Supplier<hb_tag_t>    tags_supplier  (&data->tables[0].tag, table_count, data->tables.item_size);
-  Supplier<hb_blob_t *> blobs_supplier (&data->tables[0].blob, table_count, data->tables.item_size);
+  Supplier<hb_tag_t>    tags_supplier  (&data->tables[0u].tag, table_count, data->tables.item_size);
+  Supplier<hb_blob_t *> blobs_supplier (&data->tables[0u].blob, table_count, data->tables.item_size);
   bool ret = f->serialize_single (&c,
 				  sfnt_tag,
 				  tags_supplier,
diff --git a/src/hb-machinery.hh b/src/hb-machinery.hh
index 1732d29758f66ce8f11feadc3b9360326df7ef8d..19d2e17a4bc507873a96dcc02c9b0e94d8022784 100644
--- a/src/hb-machinery.hh
+++ b/src/hb-machinery.hh
@@ -117,8 +117,8 @@ static inline Type& StructAfter(TObject &X)
   enum { min_size = (size) }
 
 #define DEFINE_SIZE_ARRAY(size, array) \
-  DEFINE_COMPILES_ASSERTION ((void) (array)[0].static_size) \
-  DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + VAR * sizeof ((array)[0])) \
+  DEFINE_COMPILES_ASSERTION ((void) (array)[0u].static_size) \
+  DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + VAR * sizeof ((array)[0u])) \
   enum { null_size = (size) }; \
   enum { min_size = (size) }