diff --git a/packages/adl-vscode/adl.tmlanguage.ts b/packages/adl-vscode/adl.tmlanguage.ts
index 34138a0d7..12b8ad50f 100644
--- a/packages/adl-vscode/adl.tmlanguage.ts
+++ b/packages/adl-vscode/adl.tmlanguage.ts
@@ -1,8 +1,12 @@
 // TextMate-based syntax highlighting is implemented in this file.
 // adl.tmLanguage.json is generated by running this script.
 
-import { writeFileSync } from "fs";
-import { OnigRegExp } from "oniguruma";
+import fs from "fs";
+import { promisify } from "util";
+import { loadWASM, OnigRegExp } from "onigasm";
+
+const readFile = promisify(fs.readFile);
+const writeFile = promisify(fs.writeFile);
 
 const schema = "https://raw.githubusercontent.com/martinring/tmlanguage/master/tmlanguage.json";
 
@@ -317,10 +321,12 @@ const grammar: Grammar = {
 };
 
 /**  Entry point, write the grammar to disk. */
-function main() {
+async function main() {
+  const onigasm = await readFile("node_modules/onigasm/lib/onigasm.wasm");
+  await loadWASM(onigasm.buffer);
   const filePath = "./dist/adl.tmlanguage.json";
   const json = emit(grammar);
-  writeFileSync(filePath, json);
+  await writeFile(filePath, json);
 }
 
 /** Emit the grammar to a JSON string matching tmlanguage.json schema. */
@@ -405,10 +411,17 @@ function processGrammar(grammar: Grammar): any {
 
   function validateRegexp(regexp: string, node: any, prop: string) {
     try {
-      new OnigRegExp(regexp);
+      new OnigRegExp(regexp).testSync("");
     } catch (err) {
+      let message: string = err.message;
+      if (/^[0-9,]+/.test(message)) {
+        // Work around for https://github.com/NeekSandhu/onigasm/issues/26
+        const array = new Uint8Array(message.split(",").map((s: string) => Number(s)));
+        const buffer = Buffer.from(array);
+        message = buffer.toString("utf-8");
+      }
       console.error(`Error: Bad regex: ${JSON.stringify({ [prop]: regexp })}`);
-      console.error(`Error: ${err.message}`);
+      console.error(`Error: ${message}`);
       console.error();
       console.error("Context:");
       console.dir(node);
@@ -418,4 +431,8 @@ function processGrammar(grammar: Grammar): any {
   }
 }
 
-main();
+main()
+  .then()
+  .catch((err) => {
+    console.log(err.stack);
+  });
diff --git a/packages/adl-vscode/package.json b/packages/adl-vscode/package.json
index 363e47b4c..ff853735e 100644
--- a/packages/adl-vscode/package.json
+++ b/packages/adl-vscode/package.json
@@ -24,8 +24,7 @@
   },
   "devDependencies": {
     "@types/node": "14.0.27",
-    "@types/oniguruma": "~7.0.1",
-    "oniguruma": "~7.2.1",
+    "onigasm": "~2.2.5",
     "typescript": "~4.1.5",
     "vsce": "^1.85.1"
   },