diff --git a/Project.toml b/Project.toml
index e4c2cffc..97b3824e 100644
--- a/Project.toml
+++ b/Project.toml
@@ -23,6 +23,7 @@ TensorKitChainRulesCoreExt = "ChainRulesCore"
 [compat]
 HalfIntegers = "1"
 LRUCache = "1.0.2"
+PackageExtensionCompat = "1"
 Strided = "2"
 TensorOperations = "4.0.6"
 TupleTools = "1.1"