diff --git a/include/engine/routing_algorithms/many_to_many.hpp b/include/engine/routing_algorithms/many_to_many.hpp
index 38abefbe2..85855576b 100644
--- a/include/engine/routing_algorithms/many_to_many.hpp
+++ b/include/engine/routing_algorithms/many_to_many.hpp
@@ -50,8 +50,8 @@ class ManyToManyRouting final
                                        const std::vector<std::size_t> &source_indices,
                                        const std::vector<std::size_t> &target_indices) const
     {
-        const auto number_of_sources = source_indices.size();
-        const auto number_of_targets = target_indices.size();
+        const auto number_of_sources = source_indices.empty() ? phantom_nodes.size() : source_indices.size();
+        const auto number_of_targets = target_indices.empty() ? phantom_nodes.size() : target_indices.size();
         const auto number_of_entries = number_of_sources * number_of_targets;
         std::vector<EdgeWeight> result_table(number_of_entries,
                                              std::numeric_limits<EdgeWeight>::max());