diff --git a/multidict/__init__.py b/multidict/__init__.py
index 0005c5ee3..51a9ccc33 100644
--- a/multidict/__init__.py
+++ b/multidict/__init__.py
@@ -22,7 +22,7 @@
     "getversion",
 )
 
-__version__ = "6.5.0"
+__version__ = "6.5.1.dev0"
 
 
 if TYPE_CHECKING or not USE_EXTENSIONS: