diff --git a/stack.yaml b/stack.yaml
index 5242b88aa..9f00e8a31 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,20 +1,12 @@
 # For more information, see: https://github.com/commercialhaskell/stack/blob/release/doc/yaml_configuration.md
 
-# Specifies the GHC version and set of packages available (e.g., lts-3.5, nightly-2015-09-21, ghc-7.10.2)
-resolver: lts-5.2
-
-# Local packages, usually specified by relative directory name
+resolver: lts-9.11
 packages:
 - '.'
-
-# Packages to be pulled from upstream that are not in the resolver (e.g., acme-missiles-0.3)
 extra-deps:
-  - ixset-1.0.6
-  - syb-with-class-0.6.1.6 # needed by ixset
-  - rss-3000.2.0.5
-
-# Override default flag values for local packages and extra-deps
+  - acid-state-0.14.3
+  - ixset-1.0.7
+  - rss-3000.2.0.6
+  - syb-with-class-0.6.1.8
 flags: {}
-
-# Extra package databases containing global packages
 extra-package-dbs: []