diff --git a/json_rpc.nimble b/json_rpc.nimble
index 4fcdaa1..03fa2d6 100644
--- a/json_rpc.nimble
+++ b/json_rpc.nimble
@@ -19,6 +19,7 @@ proc configForTests() =
   --path: "."
   --run
   --forceBuild
+  --threads: on
 
 task test, "run tests":
   configForTests()