diff --git a/panoramix/models.py b/panoramix/models.py
index 05f4a670dae9c..367c437476286 100644
--- a/panoramix/models.py
+++ b/panoramix/models.py
@@ -269,8 +269,8 @@ def grains(self):
         DB_TIME_GRAINS = {
             'presto': (
                 Grain('Time Column', '{col}'),
-                Grain('week', "date_trunc('week', {col})"),
-                Grain('month', "date_trunc('month', {col})"),
+                Grain('week', "date_trunc('week', CAST({col} AS DATE))"),
+                Grain('month', "date_trunc('month', CAST({col} AS DATE))"),
             ),
             'mysql': (
                 Grain('Time Column', '{col}'),