diff --git a/Project.toml b/Project.toml
index 3134bcb..a08acd6 100644
--- a/Project.toml
+++ b/Project.toml
@@ -19,6 +19,7 @@ SparseArrays = "2f01184e-e22b-5df5-ae63-d93ebab69eaf"
 AbstractTrees = "0.4"
 Catlab = "0.16"
 CuthillMcKee = "0.1"
+DataStructures = "0.18"
 MLStyle = "0.4"
 Metis = "1"
 PartialFunctions = "1.1"