diff --git a/qlib/__init__.py b/qlib/__init__.py
index c58de4254..16b93b12a 100644
--- a/qlib/__init__.py
+++ b/qlib/__init__.py
@@ -2,7 +2,7 @@
 # Licensed under the MIT License.
 
 
-__version__ = "0.5.1"
+__version__ = "0.5.1.dev0"
 
 import os
 import copy
diff --git a/setup.py b/setup.py
index 72a84475f..76da33b6d 100644
--- a/setup.py
+++ b/setup.py
@@ -12,7 +12,7 @@ from setuptools import find_packages, setup, Extension
 NAME = "pyqlib"
 DESCRIPTION = "A Quantitative-research Platform"
 REQUIRES_PYTHON = ">=3.5.0"
-VERSION = "0.5.1"
+VERSION = "0.5.1.dev0"
 
 # Detect Cython
 try: