diff --git a/dsp/utils/settings.py b/dsp/utils/settings.py
index 1de0ada7e..0d0846800 100644
--- a/dsp/utils/settings.py
+++ b/dsp/utils/settings.py
@@ -36,7 +36,7 @@ def __new__(cls):
                 force_reuse_cached_compilation=False,
                 compiling=False,
                 skip_logprobs=False,
-                trace=None,
+                trace=[],
                 release=0,
                 log_openai_usage=False,
                 bypass_assert=False,