diff --git a/tailbone/grids/filters.py b/tailbone/grids/filters.py
index f504664b..edce41dd 100644
--- a/tailbone/grids/filters.py
+++ b/tailbone/grids/filters.py
@@ -675,6 +675,9 @@ class AlchemyDateFilter(AlchemyGridFilter):
         Convert user input to a proper ``datetime.date`` object.
         """
         if value:
+            if isinstance(value, datetime.date):
+                return value
+
             try:
                 dt = datetime.datetime.strptime(value, '%Y-%m-%d')
             except ValueError: