diff --git a/date.inc b/date.inc
index c9e3181..a6eb930 100644
--- a/date.inc
+++ b/date.inc
@@ -98,7 +98,9 @@ class MigrateDateFieldHandler extends MigrateFieldHandler {
       }
 
       // Work from a timestamp
-      $from = MigrationBase::timestamp($from);
+      if ($from)Â {
+        $from = MigrationBase::timestamp($from);
+      }
       if ($to) {
         $to = MigrationBase::timestamp($to);
       }