diff --git a/tox.ini b/tox.ini
index f868776..16171fb 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py{27,34,35,36}-sphinx{13,14,15,16,17}
+    py{27,34,35,36}-sphinx{13,14,15,16,17,18}
     lint
     docs
 
@@ -22,6 +22,7 @@ deps = -r{toxinidir}/requirements.txt
     sphinx15: Sphinx<1.6
     sphinx16: Sphinx<1.7
     sphinx17: Sphinx<1.8
+    sphinx18: Sphinx==1.8.0b1
 commands =
     py.test {posargs}