diff --git a/lib/nntp/tiny/message.py b/lib/nntp/tiny/message.py
index c6fa86b..b353ccc 100644
--- a/lib/nntp/tiny/message.py
+++ b/lib/nntp/tiny/message.py
@@ -45,6 +45,11 @@ def parse_timestamp(timestamp: str):
 
     return parsedate_to_datetime(timestamp)
 
+class MessagePart(enum.Enum):
+    HEAD  = 1
+    BODY  = enum.auto()
+    WHOLE = enum.auto()
+
 class MessageRange():
     __slots__ = 'id', 'min', 'max',
 
diff --git a/lib/nntp/tiny/session.py b/lib/nntp/tiny/session.py
index 1ff6f84..cb16389 100644
--- a/lib/nntp/tiny/session.py
+++ b/lib/nntp/tiny/session.py
@@ -13,7 +13,7 @@ from nntp.tiny.buffer    import LineBuffer, OutputBuffer, BufferOverflow
 from nntp.tiny.db        import Database
 from nntp.tiny.response  import Response, ResponseCode
 from nntp.tiny.newsgroup import Newsgroup
-from nntp.tiny.message   import Message, MessageRange
+from nntp.tiny.message   import Message, MessageRange, MessagePart
 
 class SessionState(enum.Flag):
     ACTIVE    = 1
@@ -23,11 +23,6 @@ class SessionState(enum.Flag):
 class SessionMode(enum.Enum):
     READER = 1
 
-class MessagePart(enum.Enum):
-    HEAD  = 1
-    BODY  = enum.auto()
-    WHOLE = enum.auto()
-
 class Session():
     NNTP_VERSION      = 2
     NNTP_CAPABILITIES = [