diff --git a/rowers/views/analysisviews.py b/rowers/views/analysisviews.py
index 3a844a79..f80e114f 100644
--- a/rowers/views/analysisviews.py
+++ b/rowers/views/analysisviews.py
@@ -1067,6 +1067,7 @@ def trainingzones_view(request,userid=0,mode='rower',
 
     form = TrainingZonesForm()
     zones = 'hr'
+    date_agg = 'month'
     if request.method == 'POST': # pragma: no cover
         form = TrainingZonesForm(request.POST)
         if form.is_valid():