diff --git a/opendata_transport/__init__.py b/opendata_transport/__init__.py
index 46c1819..b154ce8 100644
--- a/opendata_transport/__init__.py
+++ b/opendata_transport/__init__.py
@@ -149,8 +149,8 @@ async def __async_get_data(self, station):
             params["id"] = station
         else:
             params["station"] = station
-        if self.date:
-            params["datetime"] = self.datetime
+        if self.datetime:
+            params["datetime"] = self.date
         if self.transportations:
             params["transportations"] = self.transportations
         if self.fields: