diff --git a/backend/chainlit/message.py b/backend/chainlit/message.py
index 0700f630a7..0b6171a767 100644
--- a/backend/chainlit/message.py
+++ b/backend/chainlit/message.py
@@ -59,7 +59,7 @@ def __post_init__(self) -> None:
             self.id = str(uuid.uuid4())
 
     @classmethod
-    def from_dict(self, _dict: StepDict):
+    def from_dict(cls, _dict: StepDict):
         type = _dict.get("type", "assistant_message")
         return Message(
             id=_dict["id"],
diff --git a/backend/chainlit/step.py b/backend/chainlit/step.py
index 1604bac8af..ee951e39f8 100644
--- a/backend/chainlit/step.py
+++ b/backend/chainlit/step.py
@@ -123,7 +123,7 @@ async def async_wrapper(*args, **kwargs):
                         logger.exception(e)
                     result = await func(*args, **kwargs)
                     try:
-                        if result and not step.output:
+                        if result is not None and not step.output:
                             step.output = result
                     except Exception as e:
                         step.is_error = True
@@ -154,7 +154,7 @@ def sync_wrapper(*args, **kwargs):
                         logger.exception(e)
                     result = func(*args, **kwargs)
                     try:
-                        if result and not step.output:
+                        if result is not None and not step.output:
                             step.output = result
                     except Exception as e:
                         step.is_error = True