diff --git a/common.nix b/common.nix
index 0fa3093..fe81d61 100644
--- a/common.nix
+++ b/common.nix
@@ -111,6 +111,7 @@
     eprover
     z3
     why3
+    graphviz
 
     nix-repl
   ] ++ (with aspellDicts; [ en de fr nl ]);