diff --git a/.travis.yml b/.travis.yml
index 3c056a7..7640295 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,12 +1,14 @@
   language: python
   python:
-    - "2.7"
     - "3.5"
     - "3.6"
+    - "3.7-dev"
 
   sudo: required
 
-  cache: pip
+  cache:
+    - pip
+    - apt
 
   addons:
     apt:
diff --git a/setup.py b/setup.py
index f995b52..fe3176f 100644
--- a/setup.py
+++ b/setup.py
@@ -28,8 +28,8 @@
     'sphinxcontrib-bibtex'
 ]
 
-if sys.version_info[:2] < (2, 7) or (3, 0) <= sys.version_info[:2] < (3, 5):
-    raise RuntimeError("Python version 2.7 or >=3.5 required.")
+if sys.version_info[:2] < (3, 5):
+    raise RuntimeError("Python version >=3.5 required.")
 
 version_py = os.path.join(os.path.dirname(
     __file__), 'graphtools', 'version.py')