diff --git a/telethon/tl/tlobject.py b/telethon/tl/tlobject.py
index 489765e2d..0ed7b015b 100644
--- a/telethon/tl/tlobject.py
+++ b/telethon/tl/tlobject.py
@@ -1,4 +1,5 @@
-from datetime import datetime
+import struct
+from datetime import datetime, date
 from threading import Event
 
 
@@ -125,6 +126,23 @@ def serialize_bytes(data):
         r.append(bytes(padding))
         return b''.join(r)
 
+    @staticmethod
+    def serialize_datetime(dt):
+        if not dt:
+            return b'\0\0\0\0'
+
+        if isinstance(dt, datetime):
+            dt = int(dt.timestamp())
+        elif isinstance(dt, date):
+            dt = int(datetime(dt.year, dt.month, dt.day, dt).timestamp())
+        elif isinstance(dt, float):
+            dt = int(dt)
+
+        if isinstance(dt, int):
+            return struct.pack('<I', dt)
+
+        raise TypeError('Cannot interpret "{}" as a date.'.format(dt))
+
     # These should be overrode
     def to_dict(self, recursive=True):
         return {}
diff --git a/telethon_generator/tl_generator.py b/telethon_generator/tl_generator.py
index 4adb5378a..3116003a5 100644
--- a/telethon_generator/tl_generator.py
+++ b/telethon_generator/tl_generator.py
@@ -540,11 +540,7 @@ def write_to_bytes(builder, arg, args, name=None):
             builder.write('TLObject.serialize_bytes({})'.format(name))
 
         elif 'date' == arg.type:  # Custom format
-            # 0 if datetime is None else int(datetime.timestamp())
-            builder.write(
-                r"b'\0\0\0\0' if {0} is None else "
-                r"struct.pack('<I', int({0}.timestamp()))".format(name)
-            )
+            builder.write('TLObject.serialize_datetime({})'.format(name))
 
         else:
             # Else it may be a custom type