diff --git a/include/crab/domains/graphs/adapt_sgraph.hpp b/include/crab/domains/graphs/adapt_sgraph.hpp
index 4ab2fd9a..7cf60457 100644
--- a/include/crab/domains/graphs/adapt_sgraph.hpp
+++ b/include/crab/domains/graphs/adapt_sgraph.hpp
@@ -199,6 +199,8 @@ template <class Weight> class AdaptGraph {
   }
 
   void growTo(vert_id v) {
+    _succs.reserve(v);
+    _preds.reserve(v);    
     while (size() < v)
       new_vertex();
   }