diff --git a/test/mtk_cache_indexing_tests.jl b/test/mtk_cache_indexing_tests.jl
index dc11a1147..633c20d82 100644
--- a/test/mtk_cache_indexing_tests.jl
+++ b/test/mtk_cache_indexing_tests.jl
@@ -1,6 +1,7 @@
 @testitem "Modeling Toolkit Cache Indexing" tags=[:downstream] begin
     using ModelingToolkit
     using ModelingToolkit: t_nounits as t
+    using SymbolicIndexingInterface
     import NonlinearSolveBase, NonlinearSolveFirstOrder
 
     @parameters p d
diff --git a/test/runtests.jl b/test/runtests.jl
index c8e8b0f4e..bfdd07b35 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -5,8 +5,10 @@ using ReTestItems, NonlinearSolve, Hwloc, InteractiveUtils, Pkg
 const GROUP = lowercase(get(ENV, "GROUP", "All"))
 
 const EXTRA_PKGS = Pkg.PackageSpec[]
-(GROUP == "all" || GROUP == "downstream") &&
+if GROUP == "all" || GROUP == "downstream"
     push!(EXTRA_PKGS, Pkg.PackageSpec("ModelingToolkit"))
+    push!(EXTRA_PKGS, Pkg.PackageSpec("SymbolicIndexingInterface"))
+end
 length(EXTRA_PKGS) ≥ 1 && Pkg.add(EXTRA_PKGS)
 
 const RETESTITEMS_NWORKERS = parse(