diff --git a/prompttools/prompttest/prompttest.py b/prompttools/prompttest/prompttest.py
index b551e1cd..332f06de 100644
--- a/prompttools/prompttest/prompttest.py
+++ b/prompttools/prompttest/prompttest.py
@@ -45,13 +45,12 @@ def prompttest(
     This enables developers to create a prompt test suite from their evaluations.
     """
 
-    model_arguments["experiment_classname"] = experiment_classname
-
     def prompttest_decorator(eval_fn: Callable):
         @wraps(eval_fn)
         def runs_test():
             if prompt_template_file and user_input_file:
                 return run_prompt_template_test_from_files(
+                    experiment_classname,
                     model_name,
                     metric_name,
                     eval_fn,
@@ -65,6 +64,7 @@ def runs_test():
                 )
             elif prompt_template and user_input:
                 return run_prompt_template_test(
+                    experiment_classname,
                     model_name,
                     metric_name,
                     eval_fn,
@@ -78,6 +78,7 @@ def runs_test():
                 )
             elif system_prompt_file and human_messages_file:
                 return run_system_prompt_test_from_files(
+                    experiment_classname,
                     model_name,
                     metric_name,
                     eval_fn,
@@ -91,6 +92,7 @@ def runs_test():
                 )
             elif system_prompt and human_messages:
                 return run_system_prompt_test(
+                    experiment_classname,
                     model_name,
                     metric_name,
                     eval_fn,
diff --git a/prompttools/prompttest/runner/prompt_template_runner.py b/prompttools/prompttest/runner/prompt_template_runner.py
index 371b8a70..37926ea0 100644
--- a/prompttools/prompttest/runner/prompt_template_runner.py
+++ b/prompttools/prompttest/runner/prompt_template_runner.py
@@ -51,13 +51,14 @@ def read(
 
     @staticmethod
     def _get_harness(
+        experiment_classname,
         model_name: str,
         prompt_template: str,
         user_inputs: List[Dict[str, str]],
         model_args: Dict[str, object],
     ) -> PromptTemplateExperimentationHarness:
         return PromptTemplateExperimentationHarness(
-            model_name, [prompt_template], user_inputs, model_arguments=model_args
+            experiment_classname, model_name, [prompt_template], user_inputs, model_arguments=model_args
         )
 
 
@@ -65,6 +66,7 @@ def _get_harness(
 
 
 def run_prompt_template_test(
+    experiment_classname,
     model_name: str,
     metric_name: str,
     eval_fn: Callable,
@@ -115,6 +117,7 @@ def run_prompt_template_test(
 
 
 def run_prompt_template_test_from_files(
+    experiment_classname,
     model_name: str,
     metric_name: str,
     eval_fn: Callable,
@@ -133,6 +136,7 @@ def run_prompt_template_test_from_files(
         prompt_template_file, user_input_file
     )
     return run_prompt_template_test(
+        experiment_classname,
         model_name,
         metric_name,
         eval_fn,
diff --git a/prompttools/prompttest/runner/runner.py b/prompttools/prompttest/runner/runner.py
index 8ec0a466..df1eb44f 100644
--- a/prompttools/prompttest/runner/runner.py
+++ b/prompttools/prompttest/runner/runner.py
@@ -51,6 +51,7 @@ def rank(self, key: str, metric_name: str, is_average: bool) -> Dict[str, float]
 
     @staticmethod
     def _get_harness(
+        experiment_classname,
         model_name: str,
         prompt_template: str,
         user_inputs: List[Dict[str, str]],
diff --git a/prompttools/prompttest/runner/system_prompt_runner.py b/prompttools/prompttest/runner/system_prompt_runner.py
index 262e9362..bdf79ce1 100644
--- a/prompttools/prompttest/runner/system_prompt_runner.py
+++ b/prompttools/prompttest/runner/system_prompt_runner.py
@@ -49,13 +49,14 @@ def read(
 
     @staticmethod
     def _get_harness(
+        experiment_classname,
         model_name: str,
         system_prompt: str,
         human_messages: List[str],
         model_args: Dict[str, object],
     ) -> SystemPromptExperimentationHarness:
         return SystemPromptExperimentationHarness(
-            model_name, [system_prompt], human_messages, model_arguments=model_args
+            experiment_classname, model_name, [system_prompt], human_messages, model_arguments=model_args
         )
 
 
@@ -113,6 +114,7 @@ def run_system_prompt_test(
 
 
 def run_system_prompt_test_from_files(
+    experiment_classname,
     model_name: str,
     metric_name: str,
     eval_fn: Callable,
@@ -131,6 +133,7 @@ def run_system_prompt_test_from_files(
         system_prompt_file, human_messages_file
     )
     return run_system_prompt_test(
+        experiment_classname,
         model_name,
         metric_name,
         eval_fn,