diff --git a/pyproject.toml b/pyproject.toml
index 288eabe..b3caa4a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,7 +2,7 @@
 # The main package is bbbb-dev;
 # bbbb is a wheel-only, optimized release for direct use by Pip etc.
 name = "bbbb-dev"
-version = "0.3.1"
+version = "0.4.0"
 description = "a Bare-Bones Build Backend (for Python packaging)"
 readme = "README.md"
 classifiers = [
diff --git a/src/bbbb.py b/src/bbbb.py
index 17df8c1..bc45e99 100644
--- a/src/bbbb.py
+++ b/src/bbbb.py
@@ -6,7 +6,7 @@
 from zipfile import ZipFile, ZIP_DEFLATED
 
 
-BBBB_VERSION = '0.3.1'
+BBBB_VERSION = '0.4.0'
 # TODO: generate a version label in the self-build process?