diff --git a/docs/en/advanced_tutorials/config.md b/docs/en/advanced_tutorials/config.md
index b9b8a05196..77c3cf0eff 100644
--- a/docs/en/advanced_tutorials/config.md
+++ b/docs/en/advanced_tutorials/config.md
@@ -528,7 +528,7 @@ Config (path: replace_data_root.py): {'dataset_type': 'CocoDataset', 'data_root'
 
 The value of `data_root` has been substituted with the value of `DATASET` as `/new/dataset/path`.
 
-It is noteworthy that both `--cfg-options` and `{{$ENV_VAR:DEF_VAL}}` allow users modified fields in command line. But there is a small difference between those two methods. Environment variable substitution occurs before the configuration parsing. If the replaced field is also involved in other fields assignment, the environment variable substitution will also affect the other fields.
+It is noteworthy that both `--cfg-options` and `{{$ENV_VAR:DEF_VAL}}` allow users to modify fields in command line. But there is a small difference between those two methods. Environment variable substitution occurs before the configuration parsing. If the replaced field is also involved in other fields assignment, the environment variable substitution will also affect the other fields.
 
 We take `demo_train.py` and `replace_data_root.py` for example. If we replace `data_root` by setting `--cfg-options data_root='/new/dataset/path'`:
 
diff --git a/mmengine/config/config.py b/mmengine/config/config.py
index 13eaf4e6e2..71ccb6a068 100644
--- a/mmengine/config/config.py
+++ b/mmengine/config/config.py
@@ -152,7 +152,7 @@ def __init__(self,
         else:
             text = ''
         super().__setattr__('_text', text)
-        if not env_variables:
+        if env_variables is None:
             env_variables = dict()
         super().__setattr__('_env_variables', env_variables)