diff --git a/pyproject.toml b/pyproject.toml
index 6469789..60a7a21 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -40,7 +40,7 @@ bed2map = "plinkliftover.bed2map:bed2mapapp"
 
 [project.optional-dependencies]
 dev = [
-    "black ==23.7.0",
+    "black ==23.12.1",
     "mypy ==1.5.1",
     "nox ==2023.4.22",
     "pytest ==7.4.0",