diff --git a/package-lock.json b/package-lock.json
index bc944c0..295745e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -13,13 +13,13 @@
       },
       "devDependencies": {
         "@domenic/eslint-config": "^4.0.1",
-        "@unicode/unicode-17.0.0": "^1.6.12",
+        "@unicode/unicode-18.0.0": "^2.0.7",
         "eslint": "^9.35.0",
         "globals": "^16.4.0",
         "regenerate": "^1.4.2"
       },
       "engines": {
-        "node": ">=18"
+        "node": ">=20"
       }
     },
     "node_modules/@domenic/eslint-config": {
@@ -252,10 +252,10 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/@unicode/unicode-17.0.0": {
-      "version": "1.6.12",
-      "resolved": "https://registry.npmjs.org/@unicode/unicode-17.0.0/-/unicode-17.0.0-1.6.12.tgz",
-      "integrity": "sha512-4IyVjMPIjHThNGZ3PSv7CTtkHrTF8YlkA2HuNAMrqnjIiN2ghCtnwUwEqjfpUT+dfBWjiZJGkiInlqF/3fPiZQ==",
+    "node_modules/@unicode/unicode-18.0.0": {
+      "version": "2.0.7",
+      "resolved": "https://registry.npmjs.org/@unicode/unicode-18.0.0/-/unicode-18.0.0-2.0.7.tgz",
+      "integrity": "sha512-sxWcUPwfbWVcSt+RPixHI468bs97A2+ftrC9b6wsGEkUTp2eod0qp7J59A+ngd4mFRISElQhPkYClhtXwNuLQw==",
       "dev": true,
       "license": "MIT"
     },
diff --git a/package.json b/package.json
index 7a5142b..9841b69 100644
--- a/package.json
+++ b/package.json
@@ -38,10 +38,10 @@
   },
   "devDependencies": {
     "@domenic/eslint-config": "^4.0.1",
-    "@unicode/unicode-17.0.0": "^1.6.12",
+    "@unicode/unicode-18.0.0": "^2.0.7",
     "eslint": "^9.35.0",
     "globals": "^16.4.0",
     "regenerate": "^1.4.2"
   },
-  "unicodeVersion": "17.0.0"
+  "unicodeVersion": "18.0.0"
 }
diff --git a/scripts/generateRegexes.js b/scripts/generateRegexes.js
index 0c6c9fd..d524110 100644
--- a/scripts/generateRegexes.js
+++ b/scripts/generateRegexes.js
@@ -12,22 +12,22 @@ main().catch(e => {
 
 async function main() {
   const cp = {
-    Mark: require(`@unicode/unicode-${unicodeVersion}/General_Category/Mark/code-points.js`),
+    Mark: (await import(`@unicode/unicode-${unicodeVersion}/General_Category/Mark/code-points.mjs`)).default,
     JT: await generateUnicodeCodePoints(`https://unicode.org/Public/${unicodeVersion}/ucd/extracted/DerivedJoiningType.txt`, ["L", "R", "D", "T"]),
     CombiningClassVirama: (await generateUnicodeCodePoints(`https://unicode.org/Public/${unicodeVersion}/ucd/extracted/DerivedCombiningClass.txt`, ["9"]))["9"],
 
     // https://tools.ietf.org/html/rfc5893#section-1.4
-    L: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Left_To_Right/code-points.js`),
-    R: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Right_To_Left/code-points.js`),
-    AL: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Arabic_Letter/code-points.js`),
-    EN: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/European_Number/code-points.js`),
-    ES: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/European_Separator/code-points.js`),
-    ET: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/European_Terminator/code-points.js`),
-    AN: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Arabic_Number/code-points.js`),
-    CS: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Common_Separator/code-points.js`),
-    NSM: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Nonspacing_Mark/code-points.js`),
-    BN: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Boundary_Neutral/code-points.js`),
-    ON: require(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Other_Neutral/code-points.js`)
+    L: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Left_To_Right/code-points.mjs`)).default,
+    R: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Right_To_Left/code-points.mjs`)).default,
+    AL: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Arabic_Letter/code-points.mjs`)).default,
+    EN: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/European_Number/code-points.mjs`)).default,
+    ES: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/European_Separator/code-points.mjs`)).default,
+    ET: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/European_Terminator/code-points.mjs`)).default,
+    AN: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Arabic_Number/code-points.mjs`)).default,
+    CS: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Common_Separator/code-points.mjs`)).default,
+    NSM: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Nonspacing_Mark/code-points.mjs`)).default,
+    BN: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Boundary_Neutral/code-points.mjs`)).default,
+    ON: (await import(`@unicode/unicode-${unicodeVersion}/Bidi_Class/Other_Neutral/code-points.mjs`)).default
   };
 
   function r(strings, ...regs) {
diff --git a/scripts/getLatestTests.js b/scripts/getLatestTests.js
index ee388c7..2d7308e 100644
--- a/scripts/getLatestTests.js
+++ b/scripts/getLatestTests.js
@@ -10,7 +10,7 @@ const { unicodeVersion } = require("../package.json");
 
 // Update this by going to https://github.com/web-platform-tests/wpt/tree/master/url/resources and pressing "y" on the
 // keyboard.
-const wptSHA = "40fc257a28faf7c378f59185235685ea8684e8f4";
+const wptSHA = "13748c36fdf9dd77cd0b34dd6b244256b365ea60";
 
 main().catch(e => {
   console.error(e);
@@ -21,17 +21,26 @@ async function main() {
   await Promise.all([
     (async () => {
       const target = path.resolve(__dirname, "../test/fixtures/IdnaTestV2.txt");
-      const response = await fetch(`https://unicode.org/Public/idna/${unicodeVersion}/IdnaTestV2.txt`);
+      const response = await fetch(`https://unicode.org/Public/${unicodeVersion}/idna/IdnaTestV2.txt`);
+      if (!response.ok) {
+        throw new Error(`Failed to fetch ${response.url}: ${response.status}`);
+      }
       await fs.writeFile(target, response.body);
     })(),
     (async () => {
       const target = path.resolve(__dirname, "../test/fixtures/toascii.json");
       const response = await fetch(`https://github.com/web-platform-tests/wpt/raw/${wptSHA}/url/resources/toascii.json`);
+      if (!response.ok) {
+        throw new Error(`Failed to fetch ${response.url}: ${response.status}`);
+      }
       await fs.writeFile(target, response.body);
     })(),
     (async () => {
       const target = path.resolve(__dirname, "../test/fixtures/IdnaTestV2ToASCII.json");
       const response = await fetch(`https://github.com/web-platform-tests/wpt/raw/${wptSHA}/url/resources/IdnaTestV2.json`);
+      if (!response.ok) {
+        throw new Error(`Failed to fetch ${response.url}: ${response.status}`);
+      }
       await fs.writeFile(target, response.body);
     })()
   ]);
diff --git a/test/toascii.js b/test/toascii.js
index df013ec..9f8cca8 100644
--- a/test/toascii.js
+++ b/test/toascii.js
@@ -32,6 +32,11 @@ describe("ToASCII", () => {
       continue;
     }
 
+    // The URL Standard bypasses IDNA processing for ASCII domains.
+    if (/^[\x00-\x7F]*$/u.test(testCase.input)) {
+      continue;
+    }
+
     let description = testCase.input;
     if (testCase.comment) {
       description += ` (${testCase.comment})`;
@@ -54,6 +59,11 @@ describe("ToASCII via IdnaTestV2.json in wpt", () => {
       continue;
     }
 
+    // The URL Standard bypasses IDNA processing for ASCII domains.
+    if (/^[\x00-\x7F]*$/u.test(testCase.input)) {
+      continue;
+    }
+
     let description = testCase.input;
     if (testCase.comment) {
       description += ` (${testCase.comment})`;