diff --git a/memgpt/functions/functions.py b/memgpt/functions/functions.py
index 233ed26e..8cade770 100644
--- a/memgpt/functions/functions.py
+++ b/memgpt/functions/functions.py
@@ -69,7 +69,7 @@ def write_function(module_name: str, function_name: str, function_code: str):
 
     # Write the function to a file
     file_path = os.path.join(USER_FUNCTIONS_DIR, f"{module_name}.py")
-    with open(file_path, "a") as f:
+    with open(file_path, "w") as f:
         f.write(function_code)
     succ, error = validate_function(module_name, file_path)