diff --git a/prolefeeder.py b/prolefeeder.py
index e398495..1b415ff 100644
--- a/prolefeeder.py
+++ b/prolefeeder.py
@@ -26,7 +26,7 @@ class DownloadForm(FlaskForm):
 def download():
     form = DownloadForm()
     if request.method == 'GET':
-        form.start_time.data = datetime.now() - timedelta(hours=1)
+        form.start_time.data = datetime.now().replace(minute=0, second=0) - timedelta(hours=1)
         form.length.data = 60
     elif form.validate_on_submit():
         output_filename = prepare_download(form)