diff --git a/Casks/paraview-nightly.rb b/Casks/paraview-nightly.rb
index 0a7dde10d..ea39e76a1 100644
--- a/Casks/paraview-nightly.rb
+++ b/Casks/paraview-nightly.rb
@@ -4,4 +4,10 @@ class ParaviewNightly < Cask
   version 'latest'
   no_checksum
   link 'paraview.app'
+    caveats <<-EOS.undent
+    This version of Paraview should be installed if your system Python
+    version is 2.7. If you are running OS X Lion (10.7) or Mountain
+    Lion (10.8) and your system Python version is 2.6, please instead
+    install paraview-nightly-lion-python27.
+   EOS
 end