diff --git a/src/hb-face.cc b/src/hb-face.cc
index 724f54d..a1ae1d7 100644
--- a/src/hb-face.cc
+++ b/src/hb-face.cc
@@ -647,8 +647,8 @@
   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,