diff --git a/lib/contourpy/_version.py b/lib/contourpy/_version.py
index 67bc602a..d0392e54 100644
--- a/lib/contourpy/_version.py
+++ b/lib/contourpy/_version.py
@@ -1 +1 @@
-__version__ = "1.3.0"
+__version__ = "1.3.1.dev1"
diff --git a/meson.build b/meson.build
index 1b77ae38..d85adbe5 100644
--- a/meson.build
+++ b/meson.build
@@ -8,7 +8,7 @@ project(
   ],
   license: 'BSD-3-Clause',
   meson_version: '>= 1.2.0',
-  version: '1.3.0',
+  version: '1.3.1.dev1',
 )
 
 # Check meson project version is the same as in _version.py