diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5cf9255..ef79bd6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## [0.0.4] - 2026-06-25
+- Avoid RangeIndex beeing modified in modifiy_timezone
+- Enhance documentation of modify_timezone
+
 ## [0.0.3] - 2026-06-23
 - Fixes in modifiy_timezone
 - Disarm dependencies to ease compatibility to designer development
diff --git a/docs/index.html b/docs/index.html
index fb8af20..ad4989a 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -600,7 +600,10 @@ <h2>Functions<a class="headerlink" href="#functions" title="Link to this heading
 <dt class="sig sig-object py" id="hdhelpers.helpers.modify_timezone">
 <span class="sig-prename descclassname"><span class="pre">hdhelpers.helpers.</span></span><span class="sig-name descname"><span class="pre">modify_timezone</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">object_to_convert</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">to_timezone</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">column_names</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">convert_index</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">True</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#hdhelpers.helpers.modify_timezone" title="Link to this definition">¶</a></dt>
 <dd><p>Converts time information of pandas objects to a certain timezone</p>
-<p>This function is applicable to index and/or columns of pd.Series or pd.DataFrame as well as for single pd.Timestamp objects.</p>
+<p>This function is applicable to index and/or columns of pd.Series or pd.DataFrame as well as for single pd.Timestamp objects.
+If time zone information is not defined in object to convert it is assumed that it is in UTC.
+Please note that column_names and convert_index are not exclusive to enable modifying both at the same time.
+To enable modifying the value of a series (not the index), please name the series and define the series’ name in column_names.</p>
 <dl class="field-list simple">
 <dt class="field-odd">Parameters<span class="colon">:</span></dt>
 <dd class="field-odd"><ul class="simple">
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index 7ee22af..11f5f46 100644
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diff --git a/pyproject.toml b/pyproject.toml
index ce5e6a4..420c0ce 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,7 +20,7 @@ exclude = [
 
 [project]
 name = "hdhelpers"
-version = "0.0.3"
+version = "0.0.4"
 description = "Streamlines metadata & timezone handling, and plotting in hetida designer components"
 readme = "README.md"
 maintainers = [
diff --git a/src/hdhelpers/__init__.py b/src/hdhelpers/__init__.py
index 7e1b713..2204863 100644
--- a/src/hdhelpers/__init__.py
+++ b/src/hdhelpers/__init__.py
@@ -5,7 +5,7 @@
 from .plot_target_settings import StatusColors
 
 # do not edit line of __version__ as it is automatically modified by running ./run build_package
-__version__ = "0.0.3"
+__version__ = "0.0.4"
 
 # function can be automated with from hdhelpers import *
 __all__ = [
diff --git a/src/hdhelpers/helpers/timezone_handling.py b/src/hdhelpers/helpers/timezone_handling.py
index 003213b..4958313 100644
--- a/src/hdhelpers/helpers/timezone_handling.py
+++ b/src/hdhelpers/helpers/timezone_handling.py
@@ -15,8 +15,8 @@ def _convert_to_optional_timezone(object_to_convert, to_timezone: str | None):
     """Convert object_to_convert to to_timezone if not None,
     or to its own timezone if aware
     or to UTC otherwise"""
-    raise NotImplementedError(
-        f"Not implemented for object_to_convert of type {type(object_to_convert).__name__}"
+    raise TypeError(
+        f"Entries to convert do not contain valid timestamps ({type(object_to_convert).__name__})"
     )
 
 
@@ -52,6 +52,9 @@ def modify_timezone[T: (pd.Timestamp, datetime.datetime, pd.Series, pd.DataFrame
     """Converts time information of pandas objects to a certain timezone
 
     This function is applicable to index and/or columns of pd.Series or pd.DataFrame as well as for single pd.Timestamp objects.
+    If time zone information is not defined in object to convert it is assumed that it is in UTC.
+    Please note that column_names and convert_index are not exclusive to enable modifying both at the same time.
+    To enable modifying the value of a series (not the index), please name the series and define the series' name in column_names.
 
     Args:
         object_to_convert (pd.Timestamp | pd.Series | pd.DataFrame): Timestamp, Series or DataFrame where timezone is modified
@@ -103,9 +106,7 @@ def modify_timezone[T: (pd.Timestamp, datetime.datetime, pd.Series, pd.DataFrame
 
         if len(column_names) == 0:
             if isinstance(object_to_convert, pd.Series):
-                new_object.index = _convert_to_optional_timezone(
-                    pd.to_datetime(new_object.index), to_timezone
-                )
+                new_object.index = _convert_to_optional_timezone(new_object.index, to_timezone)
                 msg = f"Converted index to datetime starting with {object_to_convert.index.min()}"
                 logger.debug(msg=msg)
             elif isinstance(new_object, pd.DataFrame) and "timestamp" in new_object.columns:
@@ -123,9 +124,7 @@ def modify_timezone[T: (pd.Timestamp, datetime.datetime, pd.Series, pd.DataFrame
                 )
 
         if convert_index:
-            new_object.index = _convert_to_optional_timezone(
-                pd.to_datetime(new_object.index), to_timezone
-            )
+            new_object.index = _convert_to_optional_timezone(new_object.index, to_timezone)
 
         if not isinstance(object_to_convert, pd.Series):
             new_object.attrs = object_to_convert.attrs
diff --git a/tests/helpers/test_timezone_handling.py b/tests/helpers/test_timezone_handling.py
index 808a034..c8f8b88 100644
--- a/tests/helpers/test_timezone_handling.py
+++ b/tests/helpers/test_timezone_handling.py
@@ -51,7 +51,7 @@ def test_modify_timezone_timestamp_offset(timestamp, timezone, result):
 
 def test_modify_timezone_good_dataframe(dataframe):
     local_summertime = modify_timezone(
-        dataframe, to_timezone="Europe/Berlin", column_names=["timestamp"]
+        dataframe, to_timezone="Europe/Berlin", column_names=["timestamp"], convert_index=False
     )
 
     # German summer time starts in last Sunday in March at 2 am. --> UTC 1am
@@ -109,17 +109,19 @@ def test_empty_dataframe():
     assert modified_data.empty
 
 
-def test_named_series(series_summer):
+def test_named_series_using_column_name(series_summer):
     data = pd.Series(series_summer.index)
     data.name = "timestamp"
     data.attrs = series_summer.attrs
-    modified_data = modify_timezone(data, to_timezone="Europe/Berlin", column_names=["timestamp"])
+    modified_data = modify_timezone(
+        data, to_timezone="Europe/Berlin", column_names=["timestamp"], convert_index=False
+    )
     assert modified_data[1].utcoffset() == datetime.timedelta(seconds=3600)
     assert "foo" in modified_data.attrs
 
 
 def test_named_series_using_index(series_summer):
-    data = series_summer
+    data = series_summer.copy()
     data.name = "timestamp"
     modified_data = modify_timezone(data, to_timezone="Europe/Berlin")
     assert modified_data.index[0].utcoffset() == datetime.timedelta(seconds=3600)
@@ -137,12 +139,6 @@ def test_column_not_known(series_summer, dataframe):
         _ = modify_timezone(dataframe, to_timezone="Europe/Berlin", column_names=["timestamp2"])
 
 
-def test_modify_timezone_no_tz_known(series_summer):
-    series_summer.index = series_summer.index.tz_localize(None)
-    with pytest.raises(TypeError, match="Entries to convert do not contain valid timestamps*"):
-        _ = modify_timezone(series_summer, to_timezone="Europe/Berlin")
-
-
 def test_modify_timezone_multicolumn_dataframe(multicolumn_frame):
     local_summertime = modify_timezone(
         multicolumn_frame.copy(),
@@ -200,3 +196,21 @@ def test_modify_timestamp_datetime():
     example_date = pd.to_datetime("2023-03-25 23:00", utc=True)
     modified_timestamp = modify_timezone(example_date.to_pydatetime(), to_timezone="Europe/Berlin")
     assert modified_timestamp.utcoffset() == datetime.timedelta(seconds=3600)
+
+
+def test_native_timestamp_handled_as_UTC(series_summer):
+    series_summer.index = series_summer.index.tz_localize(None)
+    modified_data = modify_timezone(series_summer.head(2), to_timezone="Europe/Berlin")
+    assert modified_data.index[0].utcoffset() == datetime.timedelta(seconds=3600)
+
+
+def test_modify_timezone_no_timestamp_as_index(series_summer):
+    with pytest.raises(TypeError, match="Entries to convert do not contain valid timestamps"):
+        _ = modify_timezone(
+            series_summer.head(2).reset_index(), to_timezone="Europe/Berlin", convert_index=True
+        )
+
+
+def test_modify_timezone_wrong_type(series_summer):
+    with pytest.raises(TypeError, match="object_to_convert is*"):
+        _ = modify_timezone(1, to_timezone="Europe/Berlin", convert_index=True)
diff --git a/uv.lock b/uv.lock
index 78341af..34e024b 100644
--- a/uv.lock
+++ b/uv.lock
@@ -263,7 +263,7 @@ wheels = [
 
 [[package]]
 name = "hdhelpers"
-version = "0.0.3"
+version = "0.0.4"
 source = { editable = "." }
 dependencies = [
     { name = "glom" },