diff --git a/Project.toml b/Project.toml
index aa6a804..79484bd 100644
--- a/Project.toml
+++ b/Project.toml
@@ -25,7 +25,7 @@ Adapt = "3, 4"
 Compat = "4"
 ITensors = "0.6.10"
 KrylovKit = "0.6, 0.7, 0.8"
-NDTensors = "0.3.31"
+NDTensors = "0.3.31, 0.4"
 Observers = "0.2"
 PackageExtensionCompat = "1"
 TimerOutputs = "0.5"