diff --git a/lib/spack/spack/__init__.py b/lib/spack/spack/__init__.py
index 8c35e70370f..f5bd2c1713b 100644
--- a/lib/spack/spack/__init__.py
+++ b/lib/spack/spack/__init__.py
@@ -11,7 +11,7 @@
 import spack.util.git
 
 #: PEP440 canonical <major>.<minor>.<micro>.<devN> string
-__version__ = "0.23.0"
+__version__ = "0.23.1.dev0"
 spack_version = __version__