diff --git a/genai-perf/genai_perf/config/input/config_command.py b/genai-perf/genai_perf/config/input/config_command.py
index e8df0ae0..01fc5f5b 100644
--- a/genai-perf/genai_perf/config/input/config_command.py
+++ b/genai-perf/genai_perf/config/input/config_command.py
@@ -206,7 +206,7 @@ class ConfigInput:
     file: str = default_field(RunConfigDefaults.FILE)
     num_dataset_entries: int = default_field(RunConfigDefaults.NUM_PROMPTS)
     seed: int = default_field(RunConfigDefaults.SEED)
-    synthetic_tokens: ConfigSyntheticTokens = ConfigSyntheticTokens()
+    synthetic_tokens: ConfigSyntheticTokens = default_field(ConfigSyntheticTokens())
 
 
 @dataclass