diff --git a/extensions/ql-vscode/.eslintrc.js b/extensions/ql-vscode/.eslintrc.js
index 503485444..a6a4d56b6 100644
--- a/extensions/ql-vscode/.eslintrc.js
+++ b/extensions/ql-vscode/.eslintrc.js
@@ -121,15 +121,6 @@ module.exports = {
         },
       },
     },
-    {
-      files: ["test/**/*"],
-      parserOptions: {
-        project: resolve(__dirname, "test/tsconfig.json"),
-      },
-      env: {
-        jest: true,
-      },
-    },
     {
       files: ["test/vscode-tests/**/*"],
       parserOptions: {
@@ -156,6 +147,18 @@ module.exports = {
         ],
       },
     },
+    {
+      files: ["test/**/*"],
+      parserOptions: {
+        project: resolve(__dirname, "test/tsconfig.json"),
+      },
+      env: {
+        jest: true,
+      },
+      rules: {
+        "@typescript-eslint/no-explicit-any": "off",
+      },
+    },
     {
       files: [
         ".eslintrc.js",
@@ -188,11 +191,5 @@ module.exports = {
         "import/no-namespace": ["error", { ignore: ["react"] }],
       },
     },
-    {
-      files: ["test/**/*", "gulpfile.ts/**/*"],
-      rules: {
-        "@typescript-eslint/no-explicit-any": "off",
-      },
-    },
   ],
 };
diff --git a/extensions/ql-vscode/gulpfile.ts/textmate-grammar.ts b/extensions/ql-vscode/gulpfile.ts/textmate-grammar.ts
new file mode 100644
index 000000000..ab61bec51
--- /dev/null
+++ b/extensions/ql-vscode/gulpfile.ts/textmate-grammar.ts
@@ -0,0 +1,91 @@
+/**
+ * A subset of the standard TextMate grammar that is used by our transformation
+ * step. For a full JSON schema, see:
+ * https://github.com/martinring/tmlanguage/blob/478ad124a21933cd4b0b65f1ee7ee18ee1f87473/tmlanguage.json
+ */
+export interface TextmateGrammar {
+  patterns: Pattern[];
+  repository?: Record<string, Pattern>;
+}
+
+/**
+ * The extended TextMate grammar as used by our transformation step. This is a superset of the
+ * standard TextMate grammar, and includes additional fields that are used by our transformation
+ * step.
+ *
+ * Any comment of the form `(?#ref-id)` in a `match`, `begin`, or `end` property will be replaced
+ * with the match text of the rule named "ref-id". If the rule named "ref-id" consists of just a
+ * `patterns` property with a list of `include` directives, the replacement pattern is the
+ * disjunction of the match patterns of all of the included rules.
+ */
+export interface ExtendedTextmateGrammar<MatchType = string> {
+  /**
+   * This represents the set of regular expression options to apply to all regular
+   * expressions throughout the file.
+   */
+  regexOptions?: string;
+  /**
+   * This element defines a map of macro names to replacement text. When a `match`, `begin`, or
+   * `end` property has a value that is a single-key map, the value is replaced with the value of the
+   * macro named by the key, with any use of `(?#)` in the macro text replaced with the text of the
+   * value of the key, surrounded by a non-capturing group (`(?:)`). For example:
+   *
+   * The `beginPattern` and `endPattern` Properties
+   * A rule can have a `beginPattern` or `endPattern` property whose value is a reference to another
+   * rule (e.g. `#other-rule`). The `beginPattern` property is replaced as follows:
+   *
+   * my-rule:
+   *   beginPattern: '#other-rule'
+   *
+   * would be transformed to
+   *
+   * my-rule:
+   *   begin: '(?#other-rule)'
+   *   beginCaptures:
+   *     '0':
+   *       patterns:
+   *       - include: '#other-rule'
+   *
+   * An `endPattern` property is transformed similary.
+   *
+   * macros:
+   *   repeat: '(?#)*'
+   * repository:
+   *   multi-letter:
+   *     match:
+   *       repeat: '[A-Za-z]'
+   *     name: scope.multi-letter
+   *
+   * would be transformed to
+   *
+   * repository:
+   *   multi-letter:
+   *     match: '(?:[A-Za-z])*'
+   *     name: scope.multi-letter
+   */
+  macros?: Record<string, string>;
+
+  patterns: Array<Pattern<MatchType>>;
+  repository?: Record<string, Pattern<MatchType>>;
+}
+
+export interface Pattern<MatchType = string> {
+  include?: string;
+  match?: MatchType;
+  begin?: MatchType;
+  end?: MatchType;
+  while?: MatchType;
+  captures?: Record<string, PatternCapture>;
+  beginCaptures?: Record<string, PatternCapture>;
+  endCaptures?: Record<string, PatternCapture>;
+  patterns?: Array<Pattern<MatchType>>;
+  beginPattern?: string;
+  endPattern?: string;
+}
+
+export interface PatternCapture {
+  name?: string;
+  patterns?: Pattern[];
+}
+
+export type ExtendedMatchType = string | Record<string, string>;
diff --git a/extensions/ql-vscode/gulpfile.ts/textmate.ts b/extensions/ql-vscode/gulpfile.ts/textmate.ts
index 25b94c5e6..0b7d2b88f 100644
--- a/extensions/ql-vscode/gulpfile.ts/textmate.ts
+++ b/extensions/ql-vscode/gulpfile.ts/textmate.ts
@@ -3,6 +3,12 @@ import { load } from "js-yaml";
 import { obj } from "through2";
 import PluginError from "plugin-error";
 import type Vinyl from "vinyl";
+import type {
+  ExtendedMatchType,
+  ExtendedTextmateGrammar,
+  Pattern,
+  TextmateGrammar,
+} from "./textmate-grammar";
 
 /**
  * Replaces all rule references with the match pattern of the referenced rule.
@@ -34,7 +40,9 @@ function replaceReferencesWithStrings(
  * @param yaml The root of the YAML document.
  * @returns A map from macro name to replacement text.
  */
-function gatherMacros(yaml: any): Map<string, string> {
+function gatherMacros<T>(
+  yaml: ExtendedTextmateGrammar<T>,
+): Map<string, string> {
   const macros = new Map<string, string>();
   for (const key in yaml.macros) {
     macros.set(key, yaml.macros[key]);
@@ -51,7 +59,7 @@ function gatherMacros(yaml: any): Map<string, string> {
  * @returns The match text for the rule. This is either the value of the rule's `match` property,
  *  or the disjunction of the match text of all of the other rules `include`d by this rule.
  */
-function getNodeMatchText(rule: any): string {
+function getNodeMatchText(rule: Pattern): string {
   if (rule.match !== undefined) {
     // For a match string, just use that string as the replacement.
     return rule.match;
@@ -78,7 +86,7 @@ function getNodeMatchText(rule: any): string {
  * @returns A map whose keys are the names of rules, and whose values are the corresponding match
  *  text of each rule.
  */
-function gatherMatchTextForRules(yaml: any): Map<string, string> {
+function gatherMatchTextForRules(yaml: TextmateGrammar): Map<string, string> {
   const replacements = new Map<string, string>();
   for (const key in yaml.repository) {
     const node = yaml.repository[key];
@@ -94,9 +102,14 @@ function gatherMatchTextForRules(yaml: any): Map<string, string> {
  * @param yaml The root of the YAML document.
  * @param action Callback to invoke on each rule.
  */
-function visitAllRulesInFile(yaml: any, action: (rule: any) => void) {
+function visitAllRulesInFile<T>(
+  yaml: ExtendedTextmateGrammar<T>,
+  action: (rule: Pattern<T>) => void,
+) {
   visitAllRulesInRuleMap(yaml.patterns, action);
-  visitAllRulesInRuleMap(yaml.repository, action);
+  if (yaml.repository) {
+    visitAllRulesInRuleMap(Object.values(yaml.repository), action);
+  }
 }
 
 /**
@@ -107,9 +120,11 @@ function visitAllRulesInFile(yaml: any, action: (rule: any) => void) {
  * @param ruleMap The map or array of rules to visit.
  * @param action Callback to invoke on each rule.
  */
-function visitAllRulesInRuleMap(ruleMap: any, action: (rule: any) => void) {
-  for (const key in ruleMap) {
-    const rule = ruleMap[key];
+function visitAllRulesInRuleMap<T>(
+  ruleMap: Array<Pattern<T>>,
+  action: (rule: Pattern<T>) => void,
+) {
+  for (const rule of ruleMap) {
     if (typeof rule === "object") {
       action(rule);
       if (rule.patterns !== undefined) {
@@ -125,16 +140,22 @@ function visitAllRulesInRuleMap(ruleMap: any, action: (rule: any) => void) {
  * @param rule The rule whose matches are to be transformed.
  * @param action The transformation to make on each match pattern.
  */
-function visitAllMatchesInRule(rule: any, action: (match: any) => any) {
+function visitAllMatchesInRule<T>(rule: Pattern<T>, action: (match: T) => T) {
   for (const key in rule) {
     switch (key) {
       case "begin":
       case "end":
       case "match":
-      case "while":
-        rule[key] = action(rule[key]);
-        break;
+      case "while": {
+        const ruleElement = rule[key];
 
+        if (!ruleElement) {
+          continue;
+        }
+
+        rule[key] = action(ruleElement);
+        break;
+      }
       default:
         break;
     }
@@ -148,14 +169,17 @@ function visitAllMatchesInRule(rule: any, action: (match: any) => any) {
  * @param rule Rule to be transformed.
  * @param key Base key of the property to be transformed.
  */
-function expandPatternMatchProperties(rule: any, key: "begin" | "end") {
-  const patternKey = `${key}Pattern`;
-  const capturesKey = `${key}Captures`;
+function expandPatternMatchProperties<T>(
+  rule: Pattern<T>,
+  key: "begin" | "end",
+) {
+  const patternKey = `${key}Pattern` as const;
+  const capturesKey = `${key}Captures` as const;
   const pattern = rule[patternKey];
   if (pattern !== undefined) {
     const patterns: string[] = Array.isArray(pattern) ? pattern : [pattern];
-    rule[key] = patterns.map((p) => `((?${p}))`).join("|");
-    const captures: { [index: string]: any } = {};
+    rule[key] = patterns.map((p) => `((?${p}))`).join("|") as T;
+    const captures: Pattern["captures"] = {};
     for (const patternIndex in patterns) {
       captures[(Number(patternIndex) + 1).toString()] = {
         patterns: [
@@ -175,7 +199,7 @@ function expandPatternMatchProperties(rule: any, key: "begin" | "end") {
  *
  * @param yaml The root of the YAML document.
  */
-function transformFile(yaml: any) {
+function transformFile(yaml: ExtendedTextmateGrammar<ExtendedMatchType>) {
   const macros = gatherMacros(yaml);
   visitAllRulesInFile(yaml, (rule) => {
     expandPatternMatchProperties(rule, "begin");
@@ -198,24 +222,29 @@ function transformFile(yaml: any) {
 
   yaml.macros = undefined;
 
-  const replacements = gatherMatchTextForRules(yaml);
+  // We have removed all object match properties, so we don't have an extended match type anymore.
+  const macrolessYaml = yaml as ExtendedTextmateGrammar;
+
+  const replacements = gatherMatchTextForRules(macrolessYaml);
   // Expand references in matches.
-  visitAllRulesInFile(yaml, (rule) => {
+  visitAllRulesInFile(macrolessYaml, (rule) => {
     visitAllMatchesInRule(rule, (match) => {
       return replaceReferencesWithStrings(match, replacements);
     });
   });
 
-  if (yaml.regexOptions !== undefined) {
-    const regexOptions = `(?${yaml.regexOptions})`;
-    visitAllRulesInFile(yaml, (rule) => {
+  if (macrolessYaml.regexOptions !== undefined) {
+    const regexOptions = `(?${macrolessYaml.regexOptions})`;
+    visitAllRulesInFile(macrolessYaml, (rule) => {
       visitAllMatchesInRule(rule, (match) => {
         return regexOptions + match;
       });
     });
 
-    yaml.regexOptions = undefined;
+    macrolessYaml.regexOptions = undefined;
   }
+
+  return macrolessYaml;
 }
 
 export function transpileTextMateGrammar() {
@@ -230,8 +259,8 @@ export function transpileTextMateGrammar() {
       } else if (file.isBuffer()) {
         const buf: Buffer = file.contents;
         const yamlText: string = buf.toString("utf8");
-        const jsonData: any = load(yamlText);
-        transformFile(jsonData);
+        const yamlData = load(yamlText) as TextmateGrammar;
+        const jsonData = transformFile(yamlData);
 
         file.contents = Buffer.from(JSON.stringify(jsonData, null, 2), "utf8");
         file.extname = ".json";