diff --git a/README_SETUP.md b/README_SETUP.md
index a172a878a7aeed3c0ab5f51587330a6f351c991f..290350105740a206ac47cb5bd761a3c6655b2c15 100644
--- a/README_SETUP.md
+++ b/README_SETUP.md
@@ -1,4 +1,5 @@
 # Installation
+python3.6 is required.
 pip install . --user
 pip install tox --user
 
diff --git a/setup.py b/setup.py
index 0f85d6d13c2b3cedcfa7ac9c1ee09be19bec9d4c..33300809a3fda5df1eb3153290c90ac715bc0dab 100755
--- a/setup.py
+++ b/setup.py
@@ -155,6 +155,7 @@ def setup_package():
         author='Timm Fitschen',
         author_email='t.fitschen@indiscale.com',
         packages=find_packages('src'),
+        python_requires='>=3.6',
         package_dir={'': 'src'},
         install_requires=['lxml>=3.6.4',
                           'PyYaml>=3.12', 'future', 'PySocks>=1.6.7'],
diff --git a/tox.ini b/tox.ini
index 97f7753720f8b8647476654518e0c65e1ec7906e..f9776382db0770e3efe1b2711f50bb5b3adde1ec 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist=py34, py35, py36, py37, py38
+envlist=py36, py37, py38
 skip_missing_interpreters = true
 
 [testenv]