diff --git a/VERSION b/VERSION
index e05cb332..7a889803 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.3.8
+1.3.9-dev0
diff --git a/setup.cfg b/setup.cfg
index 79b986d6..2be5c375 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 1.3.8
+current_version = 1.3.9-dev0
 commit = True
 tag = False
 parse = (?P<major>\d+)\.(?P<minor>\d+)\.(?P<patch>\d+)(\-(?P<release>[a-z]+)(?P<build>\d+))?
diff --git a/setup.py b/setup.py
index 76dac792..c95e7e21 100644
--- a/setup.py
+++ b/setup.py
@@ -6,7 +6,7 @@
     setup_requires.append('pytest-runner')
 
 setup(name='nb2workflow',
-      version = '1.3.8',
+      version = '1.3.9-dev0',
       description='convert notebook to workflow',
       author='Volodymyr Savchenko',
       author_email='contact@volodymyrsavchenko.com',