diff --git a/langchain/experimental/autonomous_agents/autogpt/prompt.py b/langchain/experimental/autonomous_agents/autogpt/prompt.py
index 95647b7c..909e9b0c 100644
--- a/langchain/experimental/autonomous_agents/autogpt/prompt.py
+++ b/langchain/experimental/autonomous_agents/autogpt/prompt.py
@@ -63,7 +63,7 @@ class AutoGPTPrompt(BaseChatPromptTemplate, BaseModel):
             f"from your past:\n{relevant_memory}\n\n"
         )
         memory_message = SystemMessage(content=content_format)
-        used_tokens += len(memory_message.content)
+        used_tokens += self.token_counter(memory_message.content)
         historical_messages: List[BaseMessage] = []
         for message in previous_messages[-10:][::-1]:
             message_tokens = self.token_counter(message.content)