diff --git a/test/Project.toml b/test/Project.toml
index 766f991..64ff7cb 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -10,7 +10,7 @@ Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 [compat]
 ADTypes = "1"
 Aqua = "0.8"
-CTBase = "0.25"
+CTBase = "0.25, 0.18"
 DifferentiationInterface = "0.7"
 ForwardDiff = "0.10, 1"
 MacroTools = "0.5"