diff --git a/cli/csstools-cli/package.json b/cli/csstools-cli/package.json
index ab108dcf5..4c2d37fe3 100644
--- a/cli/csstools-cli/package.json
+++ b/cli/csstools-cli/package.json
@@ -66,7 +66,7 @@
 		"css-blank-pseudo": "^7.0.1",
 		"css-has-pseudo": "^7.0.2",
 		"css-prefers-color-scheme": "^10.0.0",
-		"postcss": "^8.4.45",
+		"postcss": "^8.5.1",
 		"postcss-attribute-case-insensitive": "^7.0.1",
 		"postcss-color-functional-notation": "^7.0.7",
 		"postcss-color-hex-alpha": "^10.0.0",
diff --git a/package-lock.json b/package-lock.json
index bf5904245..596fb9652 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -92,7 +92,7 @@
 				"css-blank-pseudo": "^7.0.1",
 				"css-has-pseudo": "^7.0.2",
 				"css-prefers-color-scheme": "^10.0.0",
-				"postcss": "^8.4.45",
+				"postcss": "^8.5.1",
 				"postcss-attribute-case-insensitive": "^7.0.1",
 				"postcss-color-functional-notation": "^7.0.7",
 				"postcss-color-hex-alpha": "^10.0.0",
@@ -7287,9 +7287,9 @@
 			}
 		},
 		"node_modules/postcss": {
-			"version": "8.5.0",
-			"resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.0.tgz",
-			"integrity": "sha512-27VKOqrYfPncKA2NrFOVhP5MGAfHKLYn/Q0mz9cNQyRAKYi3VNHwYU2qKKqPCqgBmeeJ0uAFB56NumXZ5ZReXg==",
+			"version": "8.5.1",
+			"resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.1.tgz",
+			"integrity": "sha512-6oz2beyjc5VMn/KV1pPw8fliQkhBXrVn1Z3TVyqZxU8kZpzEKhBdmCFqI6ZbmGtamQvQGuU1sgPTk8ZrXDD7jQ==",
 			"funding": [
 				{
 					"type": "opencollective",
@@ -9411,7 +9411,7 @@
 			"license": "MIT",
 			"devDependencies": {
 				"@rmenke/css-tokenizer-tests": "^1.2.0",
-				"postcss": "^8.4.45",
+				"postcss": "^8.5.1",
 				"postcss-parser-tests": "^8.8.0"
 			},
 			"engines": {
@@ -9564,7 +9564,7 @@
 			],
 			"license": "MIT-0",
 			"devDependencies": {
-				"postcss": "^8.4.45"
+				"postcss": "^8.5.1"
 			},
 			"engines": {
 				"node": ">=18"
@@ -9762,7 +9762,7 @@
 			"license": "MIT-0",
 			"devDependencies": {
 				"@csstools/pack-test": "^1.0.1",
-				"postcss": "^8.4",
+				"postcss": "^8.5",
 				"stylelint": "^16.13.0",
 				"stylelint-test-rule-node": "^0.3.0"
 			},
@@ -9770,7 +9770,7 @@
 				"node": ">=18"
 			},
 			"peerDependencies": {
-				"postcss": "^8.4",
+				"postcss": "^8.5",
 				"stylelint": "^16.13.0"
 			}
 		},
diff --git a/packages/css-tokenizer/package.json b/packages/css-tokenizer/package.json
index 94ca1a0d0..d5fb5bc19 100644
--- a/packages/css-tokenizer/package.json
+++ b/packages/css-tokenizer/package.json
@@ -49,7 +49,7 @@
 	],
 	"devDependencies": {
 		"@rmenke/css-tokenizer-tests": "^1.2.0",
-		"postcss": "^8.4.45",
+		"postcss": "^8.5.1",
 		"postcss-parser-tests": "^8.8.0"
 	},
 	"scripts": {
diff --git a/packages/utilities/package.json b/packages/utilities/package.json
index 2fd635644..77ac2692e 100644
--- a/packages/utilities/package.json
+++ b/packages/utilities/package.json
@@ -51,7 +51,7 @@
 		"postcss": "^8.4"
 	},
 	"devDependencies": {
-		"postcss": "^8.4.45"
+		"postcss": "^8.5.1"
 	},
 	"scripts": {
 		"build": "rollup -c ../../rollup/default.mjs",
diff --git a/plugins-stylelint/no-at-nest-rule/package.json b/plugins-stylelint/no-at-nest-rule/package.json
index 82e54d151..a5f280423 100644
--- a/plugins-stylelint/no-at-nest-rule/package.json
+++ b/plugins-stylelint/no-at-nest-rule/package.json
@@ -35,12 +35,12 @@
 		"index.mjs"
 	],
 	"peerDependencies": {
-		"postcss": "^8.4",
+		"postcss": "^8.5",
 		"stylelint": "^16.13.0"
 	},
 	"devDependencies": {
 		"@csstools/pack-test": "^1.0.1",
-		"postcss": "^8.4",
+		"postcss": "^8.5",
 		"stylelint": "^16.13.0",
 		"stylelint-test-rule-node": "^0.3.0"
 	},