diff --git a/setup.py b/setup.py
index ae317d3e..3fd3e4e4 100644
--- a/setup.py
+++ b/setup.py
@@ -8,7 +8,7 @@
 except ImportError:
     print("ROOT is required by this library.")
 
-DEPS = ['numpy', 'PyYAML>4.*', 'future', 'pylint==2.9.6']
+DEPS = ['numpy', 'PyYAML>4.*', 'future', 'six', 'pylint==2.9.6']
 
 HERE = path.abspath(path.dirname(__file__))