diff --git a/toggl_track/__main__.py b/toggl_track/__main__.py
index 98dcca0..c727e46 100644
--- a/toggl_track/__main__.py
+++ b/toggl_track/__main__.py
@@ -1,4 +1,4 @@
 from .cli import cli
 
 if __name__ == "__main__":
-    cli()
+    auto_envvar_prefix="TOGGL"
diff --git a/toggl_track/cli.py b/toggl_track/cli.py
index 2d0229f..0103f38 100644
--- a/toggl_track/cli.py
+++ b/toggl_track/cli.py
@@ -31,12 +31,19 @@ def as_str(reference_date: dt.datetime = now) -> str:
     "--json-root",
     default=None,
 )
+@click.option(
+    "--api-token",
+    required=True,
+    envvar="TOGGL_API_TOKEN",
+    help="Toggl Track API token. Can also be set using the TOGGL_API_TOKEN environment variable.",
+)
 @click.pass_context
-def cli(ctx: click.Context, format: str, json_root: str):
+def cli(ctx: click.Context, format: str, json_root: str, api_token: str):
     "CLI tool and Python library to access Toggl Track https://toggl.com/track/"
     ctx.ensure_object(dict)
     ctx.obj['format'] = format
     ctx.obj['json_root'] = json_root
+    ctx.obj['api_token'] = api_token
 
 @cli.group()
 @click.option(
@@ -73,7 +80,7 @@ def entries(ctx: click.Context, description: List[str], project_id: List[int]):
 def list_entries(ctx: click.Context, start_date: dt.datetime, end_date: dt.datetime):
     """Returns a list of the latest time entries (default: last 24 hours)"""
 
-    client = TimeEntries.from_environment()
+    client = TimeEntries(ctx.obj['api_token'])
 
     click.echo(
         render(
@@ -106,14 +113,16 @@ def list_entries(ctx: click.Context, start_date: dt.datetime, end_date: dt.datet
 def group_by_entries(ctx: click.Context, start_date: dt.datetime, end_date: dt.datetime, field: str = "tags"):
     """Returns a list of time entries grouped by a field"""
 
-    client = TimeEntries.from_environment()
+    client = TimeEntries(ctx.obj['api_token'])
 
+    result = TimeEntriesGroupByResult(
+        client.list(start_date, end_date, project_ids=ctx.obj['project_id'], description=ctx.obj['description']),
+        key_func=GroupByCriterion(field)
+    )
+    
     click.echo(
         render(
-            TimeEntriesGroupByResult(
-                client.list(start_date, end_date, project_ids=ctx.obj['project_id'], description=ctx.obj['description']),
-                key_func=GroupByCriterion(field)
-            ),
+            result,
             format=ctx.obj['format'],
             json_root=ctx.obj['json_root'],
         ),
diff --git a/toggl_track/toggl.py b/toggl_track/toggl.py
index c466054..e0faa04 100644
--- a/toggl_track/toggl.py
+++ b/toggl_track/toggl.py
@@ -33,15 +33,15 @@ class TimeEntries(object):
     def __init__(self, api_token: str) -> None:
         self.api_token = api_token
 
-    @classmethod
-    def from_environment(cls) -> "TimeEntries":
-        """Creates a new `TimeEntries` instance from the `TOGGL_API_TOKEN` environment variable."""
-        if "TOGGL_API_TOKEN" not in os.environ:
-            raise Exception(
-                "TOGGL_API_TOKEN environment variable not found. "
-                "Please set it to your Toggl Track API token."
-            )
-        return cls(api_token=os.environ["TOGGL_API_TOKEN"])
+    # @classmethod
+    # def from_environment(cls) -> "TimeEntries":
+    #     """Creates a new `TimeEntries` instance from the `TOGGL_API_TOKEN` environment variable."""
+    #     if "TOGGL_API_TOKEN" not in os.environ:
+    #         raise Exception(
+    #             "TOGGL_API_TOKEN environment variable not found. "
+    #             "Please set it to your Toggl Track API token."
+    #         )
+    #     return cls(api_token=os.environ["TOGGL_API_TOKEN"])
 
     def list(self, start_date: datetime, end_date: datetime, description: str = None, project_ids: List[int] = []) -> Iterator[TimeEntry]:
         """Fetches the time entries between `start_date` and `end_date` dates.