diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 6184366..2fb35c5 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -18,7 +18,7 @@ This package uses [`poetry`](https://python-poetry.org/docs/master/#installation
 1. Install `poetry`
 
 ```sh
-$ curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/install-poetry.py | python -
+$ curl -sSL https://install.python-poetry.org | python3 -
 ```
 
 2. Install all project dependencies (including development/optional dependencies).
diff --git a/redcap/methods/base.py b/redcap/methods/base.py
index fa95baa..7dc1d3a 100644
--- a/redcap/methods/base.py
+++ b/redcap/methods/base.py
@@ -381,20 +381,18 @@ def _return_data(
             return response
 
         if not df_kwargs:
-            if record_type == "eav":
-                df_kwargs = {}
-            elif content == "exportFieldNames":
-                df_kwargs = {"index_col": "original_field_name"}
+            df_kwargs = {}
+
+        if "index_col" not in df_kwargs.keys() and record_type != "eav":
+            if content == "exportFieldNames":
+                df_kwargs["index_col"] = "original_field_name"
             elif content == "metadata":
-                df_kwargs = {"index_col": "field_name"}
+                df_kwargs["index_col"] = "field_name"
             elif content in ["report", "record"]:
                 if self.is_longitudinal:
-                    df_kwargs = {"index_col": [self.def_field, "redcap_event_name"]}
+                    df_kwargs["index_col"] = [self.def_field, "redcap_event_name"]
                 else:
-                    df_kwargs = {"index_col": self.def_field}
-            # catchall for other endpoints
-            else:
-                df_kwargs = {}
+                    df_kwargs["index_col"] = self.def_field
 
         response = cast(str, response)
 
diff --git a/tests/unit/test_simple_project.py b/tests/unit/test_simple_project.py
index f9589dc..d1436b4 100644
--- a/tests/unit/test_simple_project.py
+++ b/tests/unit/test_simple_project.py
@@ -414,6 +414,41 @@ def test_df_export(simple_project):
     assert hasattr(dataframe.index, "name")
 
 
+def test_df_export_empty_df_kwargs(simple_project):
+    dataframe = simple_project.export_records(format_type="df", df_kwargs={})
+
+    assert isinstance(dataframe, pd.DataFrame)
+
+    # should be set by default
+    assert dataframe.index.name == "record_id"
+
+
+def test_df_export_extend_df_kwargs_default_values(simple_project):
+    kept_columns = ["first_name", "study_id"]
+
+    dataframe = simple_project.export_records(
+        format_type="df", df_kwargs={"usecols": kept_columns + ["record_id"]}
+    )
+
+    assert isinstance(dataframe, pd.DataFrame)
+
+    # should be set by default
+    assert dataframe.index.name == "record_id"
+
+    # expected based on usecols (else would have additional columns)
+    assert dataframe.columns.tolist() == kept_columns
+
+
+def test_df_export_override_df_kwargs_default_values(simple_project):
+    dataframe = simple_project.export_records(
+        format_type="df", df_kwargs={"index_col": "first_name"}
+    )
+
+    assert isinstance(dataframe, pd.DataFrame)
+
+    assert dataframe.index.name == "first_name"
+
+
 def test_export_with_date_filters(simple_project):
     all_records = simple_project.export_records()
     limited_records = simple_project.export_records(