diff --git a/xplainet/pyproject.toml b/xplainet/pyproject.toml
index a21dcd3..77d1344 100755
--- a/xplainet/pyproject.toml
+++ b/xplainet/pyproject.toml
@@ -25,7 +25,7 @@ requests = "2.25.0"
 matplotlib = "3.3.3"
 pandas = "1.1.4" 
 nb-black = "1.0.7"
-black = "20.8b1"
+black = "26.5.1"
 jupyter_contrib_nbextensions = "0.5.1"
 
 [build-system]