diff --git a/test/downstream/Project.toml b/test/downstream/Project.toml
index 17ad5e447..d70305101 100644
--- a/test/downstream/Project.toml
+++ b/test/downstream/Project.toml
@@ -49,6 +49,7 @@ SciMLSensitivity = "7.11"
 SciMLStructures = "1.1"
 StableRNGs = "1"
 SteadyStateDiffEq = "2.2"
+StochasticDelayDiffEq = "1"
 StochasticDiffEq = "6"
 Sundials = "4.11"
 SymbolicIndexingInterface = "0.3"