diff --git a/src/pricehist/cli.py b/src/pricehist/cli.py
index 70677f9..c8670be 100644
--- a/src/pricehist/cli.py
+++ b/src/pricehist/cli.py
@@ -66,7 +66,7 @@ def build_parser():
             datetime.strptime(s, "%Y-%m-%d")
             return s
         except ValueError:
-            msg = "Not a valid date: '{0}'.".format(s)
+            msg = "Not a valid YYYY-MM-DD date: '{0}'.".format(s)
             raise argparse.ArgumentTypeError(msg)
 
     def previous_valid_date(s):
diff --git a/src/pricehist/fetch.py b/src/pricehist/fetch.py
index 20a43d3..7b190c8 100644
--- a/src/pricehist/fetch.py
+++ b/src/pricehist/fetch.py
@@ -8,6 +8,8 @@ def fetch(series, source, output, invert: bool, quantize: int, fmt) -> str:
             f"source start date of {source.start()}."
         )
 
+    # TODO warn if start date is today or later
+
     series = source.fetch(series)
 
     if invert: