diff --git a/test/cache.jl b/test/cache.jl
new file mode 100644
index 0000000..d3f7028
--- /dev/null
+++ b/test/cache.jl
@@ -0,0 +1,6 @@
+@testset "inferred" begin
+    r = [1,2]
+    x = (a = r, b = 3, c =(4, (d=5, e=r)))
+    y = @inferred(fmap(float, x))
+    @test y.a === y.c[2].e
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index e0c5970..670db20 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -10,4 +10,5 @@ using Measurements: ±
   include("base.jl")
   include("keypath.jl")
   include("flexiblefunctors.jl")
+  include("cache.jl")
 end