[repacker] fix bot failure.
diff --git a/src/graph/gsubgpos-context.hh b/src/graph/gsubgpos-context.hh
index e7c7a7b..b25d538 100644
--- a/src/graph/gsubgpos-context.hh
+++ b/src/graph/gsubgpos-context.hh
@@ -40,8 +40,7 @@
   graph_t& graph;
   unsigned lookup_list_index;
   hb_hashmap_t<unsigned, graph::Lookup*> lookups;
-  hb_map_t subtable_to_extension;
-
+  hb_hashmap_t<unsigned, unsigned> subtable_to_extension;
 
   HB_INTERNAL gsubgpos_graph_context_t (hb_tag_t table_tag_,
                                         graph_t& graph_);