diff --git a/marl_eval/utils/merge_json_files.py b/marl_eval/utils/merge_json_files.py
index 43a53f7b..5756c777 100644
--- a/marl_eval/utils/merge_json_files.py
+++ b/marl_eval/utils/merge_json_files.py
@@ -60,13 +60,17 @@ def _check_seed(concatenated_data: Dict, algo_data: Dict, seed_number: str) -> s
         return seed_number
 
 
-def concatenate_files(directory: str, json_path: str = "./concatenation") -> Dict:
+def concatenate_files(
+    input_directory: str, output_json_path: str = "concatenated_json_files/"
+) -> Dict:
     """Concatenate all json files in a directory and save the result in a json file."""
-    # Read all json files in a directory
-    json_data = _read_json_files(directory)
-# Create target folder
-    if not os.path.exists(json_path):
-        os.makedirs(json_path)
+    # Read all json files in a input_directory
+    json_data = _read_json_files(input_directory)
+
+    # Create target folder
+    if not os.path.exists(output_json_path):
+        os.makedirs(output_json_path)
+
     # Using defaultdict for automatic handling of missing keys
     concatenated_data: Dict = defaultdict(
         lambda: defaultdict(lambda: defaultdict(lambda: defaultdict(list)))
@@ -88,7 +92,9 @@ def concatenate_files(directory: str, json_path: str = "./concatenation") -> Dic
                         ] = algo_data
 
     # Save concatenated data in a json file
-    with open(f"{json_path}.json", "w") as f:
+    if output_json_path[-1] != "/":
+        output_json_path += "/"
+    with open(f"{output_json_path}metrics.json", "w") as f:
         json.dump(concatenated_data, f, indent=4)
 
     return concatenated_data