diff --git a/Lib/fontTools/__init__.py b/Lib/fontTools/__init__.py
index dace37e3c..0847da8df 100644
--- a/Lib/fontTools/__init__.py
+++ b/Lib/fontTools/__init__.py
@@ -5,6 +5,6 @@ from fontTools.misc.loggingTools import configLogger
 
 log = logging.getLogger(__name__)
 
-version = __version__ = "3.6.3"
+version = __version__ = "3.6.4.dev0"
 
 __all__ = ["version", "log", "configLogger"]
diff --git a/setup.cfg b/setup.cfg
index c480571d8..e43258528 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 3.6.3
+current_version = 3.6.4.dev0
 commit = True
 tag = False
 tag_name = {new_version}
diff --git a/setup.py b/setup.py
index d30bfe3e4..70f145f46 100755
--- a/setup.py
+++ b/setup.py
@@ -309,7 +309,7 @@ def find_data_files(manpath="share/man"):
 
 setup(
 	name="fonttools",
-	version="3.6.3",
+	version="3.6.4.dev0",
 	description="Tools to manipulate font files",
 	author="Just van Rossum",
 	author_email="just@letterror.com",