diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8860c65..3972a68 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -34,22 +34,6 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
-    # see https://github.com/actions/cache/issues/403
-    - name: Work around actions/cache bug
-      if: matrix.os == 'macos-latest'
-      run: |
-        brew update && brew install gnu-tar
-        echo PATH="/usr/local/opt/gnu-tar/libexec/gnubin:$PATH" >> $GITHUB_ENV
-
-    - uses: actions/cache@v2
-      name: Cache Stack Artifacts
-      with:
-        path: |
-          ~/.stack
-          ~/.local/bin
-          .stack-work
-        key: ${{ runner.os }}-stack-${{ hashFiles(matrix.stack_yaml) }}-6
-
     - uses: haskell/actions/setup@v1
       id: setup-haskell-stack
       name: Setup Stack
diff --git a/src/Control/Monad/Trans/OptionParser.hs b/src/Control/Monad/Trans/OptionParser.hs
index f0ea04b..bde3ef1 100644
--- a/src/Control/Monad/Trans/OptionParser.hs
+++ b/src/Control/Monad/Trans/OptionParser.hs
@@ -80,7 +80,6 @@ instance (Functor m, Monad m) => Applicative (OptionParserT o m) where
   OptionParserT mf <*> OptionParserT mx = OptionParserT (mf <*> mx)
 
 instance Monad m => Monad (OptionParserT o m) where
-  return = OptionParserT . return
   OptionParserT mx >>= f = OptionParserT (mx >>= f')
     where
       f' = unOptionParserT . f
diff --git a/src/Control/Monad/Trans/Uncertain.hs b/src/Control/Monad/Trans/Uncertain.hs
index 0b461bb..5c8e671 100644
--- a/src/Control/Monad/Trans/Uncertain.hs
+++ b/src/Control/Monad/Trans/Uncertain.hs
@@ -38,7 +38,6 @@ instance (Functor m, Monad m) => Applicative (UncertainT m) where
   UncertainT mf <*> UncertainT mx = UncertainT (mf <*> mx)
 
 instance Monad m => Monad (UncertainT m) where
-  return = UncertainT . return
   UncertainT mx >>= f = UncertainT (mx >>= f')
     where
       f' = unUncertainT . f
diff --git a/src/Data/HaskellExpr.hs b/src/Data/HaskellExpr.hs
index 1c22ae3..4bca36a 100644
--- a/src/Data/HaskellExpr.hs
+++ b/src/Data/HaskellExpr.hs
@@ -1,4 +1,5 @@
 -- | A String-based representation of simple Haskell expressions, typed via phantom types.
+{-# LANGUAGE NoPolyKinds #-}
 module Data.HaskellExpr where
 
 import Text.Printf
diff --git a/stack.yaml b/stack.yaml
index e8a8edd..40a6f58 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-17.15
+resolver: nightly-2022-03-30
 packages:
 - .
 extra-deps: []