diff --git a/sko/__init__.py b/sko/__init__.py
index babd442..f31013b 100644
--- a/sko/__init__.py
+++ b/sko/__init__.py
@@ -1,4 +1,4 @@
-__version__ = '0.5.8'
+__version__ = '0.5.9'
 
 from . import DE, GA, PSO, SA, ACA, AFSA, IA