diff --git a/stack.yaml b/stack.yaml
index 6498c22..166030a 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-3.8
+resolver: lts-3.9
 extra-deps:
     - these-0.6.1.0
     - barrier-0.1.0