diff --git a/Graph.cpp b/Graph.cpp
index 277ebcf..34c9d54 100644
--- a/Graph.cpp
+++ b/Graph.cpp
@@ -31,7 +31,7 @@ namespace data {
     m_flow.resize(m_num_vertices, std::vector<Capacity>(m_num_vertices, 0));
     m_capapcities.resize(m_num_vertices, std::vector<Capacity>(m_num_vertices, 0));
     for(auto const &arc : m_arc_list) {
-      m_capapcities.at(arc.start - 1).at(arc.end - 1) = arc.capacity;
+      m_capapcities.at(arc.start - 1).at(arc.end - 1) += arc.capacity;
     }
   }
 
diff --git a/examples/FF_killer.txt b/examples/FF_killer.txt
index 8d4b37c..749e746 100644
--- a/examples/FF_killer.txt
+++ b/examples/FF_killer.txt
@@ -2,5 +2,6 @@
 1 2 99
 1 3 99
 2 3 1
-2 4 99
+2 4 98
+2 4 1
 3 4 99