diff --git a/jsc_custom/_version.py b/jsc_custom/_version.py
index 7ed4ed4be22a8ce7908e17e634aff773cdefd869..b01fa8b95ae672ee123db67122678c18be496c02 100644
--- a/jsc_custom/_version.py
+++ b/jsc_custom/_version.py
@@ -1,4 +1,4 @@
 # __version__ should be updated using tbump, based on configuration in
 # pyproject.toml, according to instructions in RELEASE.md.
 #
-__version__ = "0.12.20"
+__version__ = "0.12.21"
diff --git a/pyproject.toml b/pyproject.toml
index 88538e66d75043a84a7c86386534636f32d625be..094962fb9971bbd02ef30c1ee71ec35ab50b5ff9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -56,7 +56,7 @@ profile = "black"
 github_url = "https://github.com/kreuzert/jupyter-jsc-custom"
 
 [tool.tbump.version]
-current = "0.12.20"
+current = "0.12.21"
 regex = '''
   (?P<major>\d+)
   \.