diff --git a/.gitignore b/.gitignore
index 997af62..7104f1d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -26,3 +26,4 @@ cabal.project.local
 cabal.project.local~
 .HTF/
 .ghc.environment.*
+hie.yaml
diff --git a/stack.yaml b/stack.yaml
index 2bc84ed..5c8537e 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -17,7 +17,7 @@
 #
 # resolver: ./custom-snapshot.yaml
 # resolver: https://example.com/snapshots/2018-01-01.yaml
-resolver: lts-20.12
+resolver: lts-20.16
 
 
 # User packages to be built.
diff --git a/stack.yaml.lock b/stack.yaml.lock
index 8ede860..33f278d 100644
--- a/stack.yaml.lock
+++ b/stack.yaml.lock
@@ -13,7 +13,7 @@ packages:
     hackage: chronos-1.1.5
 snapshots:
 - completed:
-    sha256: af5d667f6096e535b9c725a72cffe0f6c060e0568d9f9eeda04caee70d0d9d2d
-    size: 649133
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/20/12.yaml
-  original: lts-20.12
+    sha256: dad15e2ec0c09280a5c2e07190fb18710fc54472f029f34f861f686540824d81
+    size: 649592
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/20/16.yaml
+  original: lts-20.16