diff --git a/Brewfile b/Brewfile
index b74d1b2..61f7eeb 100644
--- a/Brewfile
+++ b/Brewfile
@@ -3,7 +3,9 @@ brew "make"
 brew "shfmt"
 brew "swift-format"
 brew "swiftformat"
-brew "swiftlint"
+
+# Already installed on GitHub Actions runner.
+# brew "swiftlint"
 
 tap "kylef/formulae"
 brew "swiftenv"
diff --git a/Brewfile.lock.json b/Brewfile.lock.json
index 8effcc8..ce7247b 100644
--- a/Brewfile.lock.json
+++ b/Brewfile.lock.json
@@ -136,29 +136,6 @@
           }
         }
       },
-      "swiftlint": {
-        "version": "0.43.1",
-        "bottle": {
-          "rebuild": 0,
-          "cellar": ":any_skip_relocation",
-          "prefix": "/opt/homebrew",
-          "root_url": "https://homebrew.bintray.com/bottles",
-          "files": {
-            "arm64_big_sur": {
-              "url": "https://homebrew.bintray.com/bottles/swiftlint-0.43.1.arm64_big_sur.bottle.tar.gz",
-              "sha256": "e1b633e61793b924f5875e4812b49184c91fc6580bfd497ab650fe13fbbe8d8f"
-            },
-            "big_sur": {
-              "url": "https://homebrew.bintray.com/bottles/swiftlint-0.43.1.big_sur.bottle.tar.gz",
-              "sha256": "90faabe65db0f6bc43c3752b3b6d541e7e23cd0f368035dcef57503d74ed9581"
-            },
-            "catalina": {
-              "url": "https://homebrew.bintray.com/bottles/swiftlint-0.43.1.catalina.bottle.tar.gz",
-              "sha256": "c1396dec887bf6d7986c35f38101955fb1a5c527ad4cd459174b3841dfa62239"
-            }
-          }
-        }
-      },
       "swiftenv": {
         "version": "1.4.0",
         "bottle": false
@@ -175,7 +152,7 @@
       "big_sur": {
         "HOMEBREW_VERSION": "3.0.9-55-g3bfa59b",
         "HOMEBREW_PREFIX": "/opt/homebrew",
-        "Homebrew/homebrew-core": "842e8819cadc9ca4d8dcdea138146dd235e35cb9",
+        "Homebrew/homebrew-core": "79dc67e162fb8d7b82ef38f88e7363647e35aa7d",
         "CLT": "12.4.0.0.1.1610135815",
         "Xcode": "12.4",
         "macOS": "11.2.3"
diff --git a/script/format b/script/format
index 0d36606..02969fd 100755
--- a/script/format
+++ b/script/format
@@ -15,7 +15,7 @@ echo "==> 🚨 Formatting mas"
 
 for LINTER in shfmt swift-format swiftformat swiftlint; do
   if [[ ! -x "$(command -v ${LINTER})" ]]; then
-    echo "error: ${LINTER} is not installed. Run script/bootstrap."
+    echo "error: ${LINTER} is not installed. Run 'script/bootstrap' or 'brew install ${LINTER}'."
     exit 1
   fi
 done
diff --git a/script/lint b/script/lint
index 354c06a..82357e0 100755
--- a/script/lint
+++ b/script/lint
@@ -14,7 +14,7 @@ echo "==> 🚨 Linting mas"
 
 for LINTER in git swift-format swiftformat swiftlint; do
   if [[ ! -x "$(command -v ${LINTER})" ]]; then
-    echo "error: ${LINTER} is not installed. Run script/bootstrap."
+    echo "error: ${LINTER} is not installed. Run 'script/bootstrap' or 'brew install ${LINTER}'."
     exit 1
   fi
 done