diff --git a/src/sagemaker_huggingface_inference_toolkit/handler_service.py b/src/sagemaker_huggingface_inference_toolkit/handler_service.py
index 84ba47a..755a8df 100644
--- a/src/sagemaker_huggingface_inference_toolkit/handler_service.py
+++ b/src/sagemaker_huggingface_inference_toolkit/handler_service.py
@@ -301,23 +301,29 @@ def validate_and_initialize_user_module(self):
                 )
             self.log_func_implementation_found_or_not(load_fn, MODEL_FN)
             if load_fn is not None:
-                self.load_extra_arg = self.function_extra_arg(self.load, load_fn)
+                self.load_extra_arg = self.function_extra_arg(HuggingFaceHandlerService.load, load_fn)
                 self.load = load_fn
             self.log_func_implementation_found_or_not(preprocess_fn, INPUT_FN)
             if preprocess_fn is not None:
-                self.preprocess_extra_arg = self.function_extra_arg(self.preprocess, preprocess_fn)
+                self.preprocess_extra_arg = self.function_extra_arg(
+                    HuggingFaceHandlerService.preprocess, preprocess_fn
+                )
                 self.preprocess = preprocess_fn
             self.log_func_implementation_found_or_not(predict_fn, PREDICT_FN)
             if predict_fn is not None:
-                self.predict_extra_arg = self.function_extra_arg(self.predict, predict_fn)
+                self.predict_extra_arg = self.function_extra_arg(HuggingFaceHandlerService.predict, predict_fn)
                 self.predict = predict_fn
             self.log_func_implementation_found_or_not(postprocess_fn, OUTPUT_FN)
             if postprocess_fn is not None:
-                self.postprocess_extra_arg = self.function_extra_arg(self.postprocess, postprocess_fn)
+                self.postprocess_extra_arg = self.function_extra_arg(
+                    HuggingFaceHandlerService.postprocess, postprocess_fn
+                )
                 self.postprocess = postprocess_fn
             self.log_func_implementation_found_or_not(transform_fn, TRANSFORM_FN)
             if transform_fn is not None:
-                self.transform_extra_arg = self.function_extra_arg(self.transform_fn, transform_fn)
+                self.transform_extra_arg = self.function_extra_arg(
+                    HuggingFaceHandlerService.transform_fn, transform_fn
+                )
                 self.transform_fn = transform_fn
         else:
             logger.info(
@@ -342,8 +348,15 @@ def function_extra_arg(self, default_func, func):
         1. the handle function takes context
         2. the handle function does not take context
         """
-        num_default_func_input = len(signature(default_func).parameters)
-        num_func_input = len(signature(func).parameters)
+        default_params = signature(default_func).parameters
+        func_params = signature(func).parameters
+
+        if "self" in default_params:
+            num_default_func_input = len(default_params) - 1
+        else:
+            num_default_func_input = len(default_params)
+
+        num_func_input = len(func_params)
         if num_default_func_input == num_func_input:
             # function takes context
             extra_args = [self.context]
diff --git a/tests/unit/test_handler_service_with_context.py b/tests/unit/test_handler_service_with_context.py
index a8b5b71..1790e40 100644
--- a/tests/unit/test_handler_service_with_context.py
+++ b/tests/unit/test_handler_service_with_context.py
@@ -166,3 +166,23 @@ def test_validate_and_initialize_user_module_transform_fn():
         inference_handler.transform_fn("model", "dummy", "application/json", "application/json", CONTEXT)
         == "output dummy"
     )
+
+
+def test_validate_and_initialize_user_module_transform_fn_race_condition():
+    os.environ["SAGEMAKER_PROGRAM"] = "inference_tranform_fn.py"
+    inference_handler = handler_service.HuggingFaceHandlerService()
+    model_dir = os.path.join(os.getcwd(), "tests/resources/model_transform_fn_with_context")
+    CONTEXT = Context("dummy", model_dir, {}, 1, -1, "1.1.4")
+
+    # Similuate 2 threads bypassing check in handle() - calling initialize twice
+    inference_handler.initialize(CONTEXT)
+    inference_handler.initialize(CONTEXT)
+
+    CONTEXT.request_processor = [RequestProcessor({"Content-Type": "application/json"})]
+    CONTEXT.metrics = MetricsStore(1, MODEL)
+    assert "output" in inference_handler.handle([{"body": b"dummy"}], CONTEXT)[0]
+    assert inference_handler.load({}, CONTEXT) == "Loading inference_tranform_fn.py"
+    assert (
+        inference_handler.transform_fn("model", "dummy", "application/json", "application/json", CONTEXT)
+        == "output dummy"
+    )
diff --git a/tests/unit/test_handler_service_without_context.py b/tests/unit/test_handler_service_without_context.py
index 37c37e7..40fd4c3 100644
--- a/tests/unit/test_handler_service_without_context.py
+++ b/tests/unit/test_handler_service_without_context.py
@@ -154,3 +154,20 @@ def test_validate_and_initialize_user_module_transform_fn():
     assert "output" in inference_handler.handle([{"body": b"dummy"}], CONTEXT)[0]
     assert inference_handler.load({}) == "Loading inference_tranform_fn.py"
     assert inference_handler.transform_fn("model", "dummy", "application/json", "application/json") == "output dummy"
+
+
+def test_validate_and_initialize_user_module_transform_fn_race_condition():
+    os.environ["SAGEMAKER_PROGRAM"] = "inference_tranform_fn.py"
+    inference_handler = handler_service.HuggingFaceHandlerService()
+    model_dir = os.path.join(os.getcwd(), "tests/resources/model_transform_fn_without_context")
+    CONTEXT = Context("dummy", model_dir, {}, 1, -1, "1.1.4")
+
+    # Similuate 2 threads bypassing check in handle() - calling initialize twice
+    inference_handler.initialize(CONTEXT)
+    inference_handler.initialize(CONTEXT)
+
+    CONTEXT.request_processor = [RequestProcessor({"Content-Type": "application/json"})]
+    CONTEXT.metrics = MetricsStore(1, MODEL)
+    assert "output" in inference_handler.handle([{"body": b"dummy"}], CONTEXT)[0]
+    assert inference_handler.load({}) == "Loading inference_tranform_fn.py"
+    assert inference_handler.transform_fn("model", "dummy", "application/json", "application/json") == "output dummy"