diff --git a/Project.toml b/Project.toml
index c7fe0f4..4a658ef 100644
--- a/Project.toml
+++ b/Project.toml
@@ -10,6 +10,7 @@ LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 
 [compat]
+DataStructures = "0.18"
 ITensors = "0.3"
 julia = "1"