diff --git a/lib/mosaik/metrics/cohesion.rb b/lib/mosaik/metrics/cohesion.rb
index d39cb57..103fa43 100644
--- a/lib/mosaik/metrics/cohesion.rb
+++ b/lib/mosaik/metrics/cohesion.rb
@@ -35,7 +35,8 @@ def evaluate
 
           # Calculate sum of edges between vertices in the cluster
           sum = vertices_in_cluster
-            .flat_map { |v| v.edges.filter_map { |i, e| e if i.in?(vertices_in_cluster_id) } }
+            .map { |v| v.edges.slice(*vertices_in_cluster_id).values }
+            .flatten(2)
             .uniq
             .count
 
diff --git a/lib/mosaik/metrics/coupling.rb b/lib/mosaik/metrics/coupling.rb
index ccad9b4..1c3f16f 100644
--- a/lib/mosaik/metrics/coupling.rb
+++ b/lib/mosaik/metrics/coupling.rb
@@ -21,10 +21,10 @@ def evaluate
 
           # Iterate over all vertices in the cluster
           vertices_in_cluster.each do |v|
-            v.edges.each do |i, e|
+            v.edges.each do |i, es|
               next if i.in? vertices_in_cluster_id
 
-              coupling_c += e.attributes.fetch(:weight, 0.0)
+              coupling_c += es.sum { |e| e.attributes.fetch(:weight, 0.0) }
             end
           end