diff --git a/test/compiler/inference.jl b/test/compiler/inference.jl
index 1a5ac13684c29..73dbedf8a39d5 100644
--- a/test/compiler/inference.jl
+++ b/test/compiler/inference.jl
@@ -3095,7 +3095,7 @@ end
 @test Base.return_types(f_bare_argument, (Int,))[1] == Int
 
 # issue #39611
-Base.return_types((Union{Int,Nothing},)) do x
+@test Base.return_types((Union{Int,Nothing},)) do x
     if x === nothing || x < 0
         return 0
     end