diff --git a/stack.yaml b/stack.yaml
index e111633e1..6902e47df 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -4,7 +4,7 @@ nix:
   pure: false
   packages: [perl gmp ncurses zlib]
 
-resolver: nightly-2021-11-19
+resolver: nightly-2021-12-16
 
 packages:
 - hledger-lib
diff --git a/stack8.10.yaml b/stack8.10.yaml
index d657c8c0c..e73f3b602 100644
--- a/stack8.10.yaml
+++ b/stack8.10.yaml
@@ -1,10 +1,10 @@
-# stack build plan using GHC 8.10.4
+# stack build plan using GHC 8.10.7
 
 nix:
   pure: false
   packages: [perl gmp ncurses zlib]
 
-resolver: lts-18.16
+resolver: lts-18.18
 
 packages:
 - hledger-lib
@@ -14,7 +14,7 @@ packages:
 
 extra-deps:
 # for hledger-lib:
-- doctest-0.18.1
+- doctest-0.20.0
 # for hledger:
 # for hledger-ui:
 # for hledger-web: