diff --git a/tests/config.nims b/tests/config.nims
index 4b5a5e3a21..b08a697a8a 100644
--- a/tests/config.nims
+++ b/tests/config.nims
@@ -32,7 +32,6 @@ hint("Processing", off)
 
 # experimental APIs are enabled in testament, refs https://github.com/timotheecour/Nim/issues/575
 # sync with `kochdocs.docDefines` or refactor.
-switch("define", "nimExperimentalAsyncjsThen")
 switch("define", "nimExperimentalLinenoiseExtra")
 
 # preview APIs are expected to be the new default in upcoming versions