diff --git a/docs/conf.py b/docs/conf.py
index 63390be..df200b0 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -8,7 +8,7 @@
 
 project = "modflow-devtools"
 author = "MODFLOW Team"
-release = '1.5.0'
+release = '1.6.0.dev0'
 
 # -- General configuration ---------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
diff --git a/modflow_devtools/__init__.py b/modflow_devtools/__init__.py
index 7614347..1a79d68 100644
--- a/modflow_devtools/__init__.py
+++ b/modflow_devtools/__init__.py
@@ -1,6 +1,6 @@
 __author__ = "Joseph D. Hughes"
 __date__ = "May 15, 2024"
-__version__ = "1.5.0"
+__version__ = "1.6.0.dev0"
 __maintainer__ = "Joseph D. Hughes"
 __email__ = "jdhughes@usgs.gov"
 __status__ = "Production"
diff --git a/version.txt b/version.txt
index 3e1ad72..24e787f 100644
--- a/version.txt
+++ b/version.txt
@@ -1 +1 @@
-1.5.0
\ No newline at end of file
+1.6.0.dev0
\ No newline at end of file
diff --git a/version.txt.lock b/version.txt.lock
deleted file mode 100644
index e69de29..0000000