diff --git a/src/crab_utils/adapt_sgraph.hpp b/src/crab_utils/adapt_sgraph.hpp
index e131044f0..dfd5cf018 100644
--- a/src/crab_utils/adapt_sgraph.hpp
+++ b/src/crab_utils/adapt_sgraph.hpp
@@ -338,6 +338,8 @@ class AdaptGraph final {
     }
 
     void growTo(size_t v) {
+        _succs.reserve(v);
+        _preds.reserve(v);
         while (size() < v) {
             new_vertex();
         }