diff --git a/ext/TensorKitChainRulesCoreExt.jl b/ext/TensorKitChainRulesCoreExt.jl
index 8a5f4194..345fb6da 100644
--- a/ext/TensorKitChainRulesCoreExt.jl
+++ b/ext/TensorKitChainRulesCoreExt.jl
@@ -11,7 +11,11 @@ import TensorOperations as TO
 using TensorOperations: Backend, promote_contract
 using VectorInterface: promote_scale, promote_add
 
-ext = Base.get_extension(TensorOperations, :TensorOperationsChainRulesCoreExt)
+ext = @static if isdefined(Base, :get_extension)
+    Base.get_extension(TensorOperations, :TensorOperationsChainRulesCoreExt)
+else
+    TensorOperations.TensorOperationsChainRulesCoreExt
+end
 const _conj = ext._conj
 const trivtuple = ext.trivtuple
 
diff --git a/test/ad.jl b/test/ad.jl
index e47d5c1b..836cd70f 100644
--- a/test/ad.jl
+++ b/test/ad.jl
@@ -4,7 +4,11 @@ using Random
 using FiniteDifferences
 using LinearAlgebra
 
-_repartition = Base.get_extension(TensorKit, :TensorKitChainRulesCoreExt)._repartition
+const _repartition = @static if isdefined(Base, :get_extension)
+    Base.get_extension(TensorKit, :TensorKitChainRulesCoreExt)._repartition
+else
+    TensorKit.TensorKitChainRulesCoreExt._repartition
+end
 
 # Test utility
 # -------------