diff --git a/packages/ruleset-migrator/package.json b/packages/ruleset-migrator/package.json
index 43df39b812..1e2b2b05d6 100644
--- a/packages/ruleset-migrator/package.json
+++ b/packages/ruleset-migrator/package.json
@@ -21,7 +21,7 @@
     "url": "https://github.com/stoplightio/spectral.git"
   },
   "dependencies": {
-    "@stoplight/json": "3.17.0",
+    "@stoplight/json": "~3.17.0",
     "@stoplight/ordered-object-literal": "1.0.2",
     "@stoplight/path": "1.3.2",
     "@stoplight/spectral-functions": "^1.0.0",
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/extends-variant-8/output.cjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/extends-variant-8/output.cjs
index 12891d8d81..9cc61f982b 100644
--- a/packages/ruleset-migrator/src/__tests__/__fixtures__/extends-variant-8/output.cjs
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/extends-variant-8/output.cjs
@@ -6,9 +6,9 @@ module.exports = {
       extends: [
         {
           rules: {
-            "my-rule": {
-              message: "ruleset 2",
-              given: "$",
+            'my-rule': {
+              message: 'ruleset 2',
+              given: '$',
               then: {
                 function: falsy,
               },
@@ -17,9 +17,9 @@ module.exports = {
         },
         {
           rules: {
-            "my-rule": {
-              message: "ruleset 3",
-              given: "$",
+            'my-rule': {
+              message: 'ruleset 3',
+              given: '$',
               then: {
                 function: pascalCase,
               },
@@ -28,9 +28,9 @@ module.exports = {
         },
       ],
       rules: {
-        "my-rule": {
-          message: "ruleset",
-          given: "$",
+        'my-rule': {
+          message: 'ruleset',
+          given: '$',
           then: {
             function: truthy,
           },
@@ -40,5 +40,5 @@ module.exports = {
   ],
 };
 function _interopDefault(ex) {
-  return ex && typeof ex === "object" && "default" in ex ? ex["default"] : ex;
+  return ex && typeof ex === 'object' && 'default' in ex ? ex['default'] : ex;
 }
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/extends-variant-8/output.mjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/extends-variant-8/output.mjs
index 56e3591825..33e8fe2d86 100644
--- a/packages/ruleset-migrator/src/__tests__/__fixtures__/extends-variant-8/output.mjs
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/extends-variant-8/output.mjs
@@ -1,5 +1,5 @@
-import { falsy, truthy } from "@stoplight/spectral-functions";
-import pascalCase from "/.tmp/spectral/extends-variant-8/assets/shared/functions/pascalCase.js";
+import { falsy, truthy } from '@stoplight/spectral-functions';
+import pascalCase from '/.tmp/spectral/extends-variant-8/assets/shared/functions/pascalCase.js';
 export default {
   extends: [
     {
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-4/output.cjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-4/output.cjs
index aaf98e740c..904b4ef2af 100644
--- a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-4/output.cjs
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-4/output.cjs
@@ -1,13 +1,13 @@
-const { oas3, oas3_1 } = require('@stoplight/spectral-formats');
-const oas3$0 = _interopDefault(require('/.tmp/spectral/functions-variant-4/functions/oas3.js'));
+const { oas3: oas3$0, oas3_1 } = require('@stoplight/spectral-formats');
+const oas3 = _interopDefault(require('/.tmp/spectral/functions-variant-4/functions/oas3.js'));
 module.exports = {
-  formats: [oas3, oas3_1],
+  formats: [oas3$0, oas3_1],
   rules: {
     rule: {
       given: '$',
       then: [
         {
-          function: oas3$0,
+          function: oas3,
         },
       ],
     },
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-4/output.mjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-4/output.mjs
index 0561856a47..6699691bff 100644
--- a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-4/output.mjs
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-4/output.mjs
@@ -1,13 +1,13 @@
-import { oas3, oas3_1 } from '@stoplight/spectral-formats';
-import oas3$0 from '/.tmp/spectral/functions-variant-4/functions/oas3.js';
+import { oas3 as oas3$0, oas3_1 } from '@stoplight/spectral-formats';
+import oas3 from '/.tmp/spectral/functions-variant-4/functions/oas3.js';
 export default {
-  formats: [oas3, oas3_1],
+  formats: [oas3$0, oas3_1],
   rules: {
     rule: {
       given: '$',
       then: [
         {
-          function: oas3$0,
+          function: oas3,
         },
       ],
     },
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-5/output.cjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-5/output.cjs
new file mode 100644
index 0000000000..5455b84d0b
--- /dev/null
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-5/output.cjs
@@ -0,0 +1,14 @@
+const donothing = _interopDefault(require('/.tmp/spectral/functions-variant-5/custom-functions/do-nothing.js'));
+module.exports = {
+  rules: {
+    rule: {
+      given: '$',
+      then: {
+        function: donothing,
+      },
+    },
+  },
+};
+function _interopDefault(ex) {
+  return ex && typeof ex === 'object' && 'default' in ex ? ex['default'] : ex;
+}
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-5/output.mjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-5/output.mjs
new file mode 100644
index 0000000000..86b1a247a3
--- /dev/null
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-5/output.mjs
@@ -0,0 +1,11 @@
+import donothing from '/.tmp/spectral/functions-variant-5/custom-functions/do-nothing.js';
+export default {
+  rules: {
+    rule: {
+      given: '$',
+      then: {
+        function: donothing,
+      },
+    },
+  },
+};
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-5/ruleset.yaml b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-5/ruleset.yaml
new file mode 100644
index 0000000000..440b085b74
--- /dev/null
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-5/ruleset.yaml
@@ -0,0 +1,8 @@
+rules:
+  rule:
+    given: $
+    then:
+      function: do-nothing
+functionsDir: custom-functions
+functions:
+  - do-nothing
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-6/output.cjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-6/output.cjs
new file mode 100644
index 0000000000..15a66e3412
--- /dev/null
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-6/output.cjs
@@ -0,0 +1,11 @@
+const { truthy } = require('@stoplight/spectral-functions');
+module.exports = {
+  rules: {
+    rule: {
+      given: '$',
+      then: {
+        function: truthy,
+      },
+    },
+  },
+};
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-6/output.mjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-6/output.mjs
new file mode 100644
index 0000000000..319df78e4e
--- /dev/null
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-6/output.mjs
@@ -0,0 +1,11 @@
+import { truthy } from '@stoplight/spectral-functions';
+export default {
+  rules: {
+    rule: {
+      given: '$',
+      then: {
+        function: truthy,
+      },
+    },
+  },
+};
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-6/ruleset.yaml b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-6/ruleset.yaml
new file mode 100644
index 0000000000..1d6fba1cb2
--- /dev/null
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-6/ruleset.yaml
@@ -0,0 +1,6 @@
+rules:
+  rule:
+    given: $
+    then:
+      function: truthy
+functionsDir: custom-fns
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-7/output.cjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-7/output.cjs
new file mode 100644
index 0000000000..262a10c6e8
--- /dev/null
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-7/output.cjs
@@ -0,0 +1,10 @@
+module.exports = {
+  rules: {
+    rule: {
+      given: '$',
+      then: {
+        function: void 0,
+      },
+    },
+  },
+};
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-7/output.mjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-7/output.mjs
new file mode 100644
index 0000000000..d40e734b52
--- /dev/null
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-7/output.mjs
@@ -0,0 +1,10 @@
+export default {
+  rules: {
+    rule: {
+      given: '$',
+      then: {
+        function: void 0,
+      },
+    },
+  },
+};
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-7/ruleset.yaml b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-7/ruleset.yaml
new file mode 100644
index 0000000000..6a52ee783e
--- /dev/null
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/functions-variant-7/ruleset.yaml
@@ -0,0 +1,5 @@
+rules:
+  rule:
+    given: $
+    then:
+      function: do-nothing
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/output.cjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/output.cjs
index 981ba5ab6e..786caeebb7 100644
--- a/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/output.cjs
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/output.cjs
@@ -1,4 +1,5 @@
 const { oas2 } = require('@stoplight/spectral-formats');
+const { truthy } = require('@stoplight/spectral-functions');
 module.exports = {
   rules: {
     'oas3-schema': 'error',
@@ -11,7 +12,7 @@ module.exports = {
       given:
         "$.paths.*[?( @property === 'get' || @property === 'put' || @property === 'post' || @property === 'delete' || @property === 'options' || @property === 'head' || @property === 'patch' || @property === 'trace' )]",
       then: {
-        function: void 0,
+        function: truthy,
         functionOptions: null,
       },
     },
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/output.mjs b/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/output.mjs
index 5bcb82491e..5373a77e16 100644
--- a/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/output.mjs
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/output.mjs
@@ -1,4 +1,5 @@
 import { oas2 } from '@stoplight/spectral-formats';
+import { truthy } from '@stoplight/spectral-functions';
 export default {
   rules: {
     'oas3-schema': 'error',
@@ -11,7 +12,7 @@ export default {
       given:
         "$.paths.*[?( @property === 'get' || @property === 'put' || @property === 'post' || @property === 'delete' || @property === 'options' || @property === 'head' || @property === 'patch' || @property === 'trace' )]",
       then: {
-        function: void 0,
+        function: truthy,
         functionOptions: null,
       },
     },
diff --git a/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/ruleset.yaml b/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/ruleset.yaml
index 9ce991d8de..22a5b2fb83 100644
--- a/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/ruleset.yaml
+++ b/packages/ruleset-migrator/src/__tests__/__fixtures__/rules-variant-1/ruleset.yaml
@@ -12,5 +12,5 @@ rules:
       "$.paths.*[?( @property === 'get' || @property === 'put' || @property === 'post' || @property === 'delete' ||
       @property === 'options' || @property === 'head' || @property === 'patch' || @property === 'trace' )]"
     then:
-      function: oasOpFormDataConsumeCheck
+      function: truthy
       functionOptions: null
diff --git a/packages/ruleset-migrator/src/index.ts b/packages/ruleset-migrator/src/index.ts
index f09df49544..2c24542ae2 100644
--- a/packages/ruleset-migrator/src/index.ts
+++ b/packages/ruleset-migrator/src/index.ts
@@ -50,18 +50,18 @@ export async function migrateRuleset(filepath: string, opts: MigrationOptions):
   };
 
   for (const transformer of transformers) {
-    transformer(ctx);
+    transformer((...hook) => void ctx.hooks.add(hook));
   }
 
-  tree.ruleset = await process(ruleset, hooks);
+  tree.ruleset = await process(ruleset, ctx);
 
   return tree.toString();
 }
 
-async function _process(input: unknown, hooks: Set<Hook>, path: string): Promise<ExpressionKind | null> {
-  for (const [pattern, fn] of hooks) {
+async function _process(input: unknown, ctx: TransformerCtx, path: string): Promise<ExpressionKind | null> {
+  for (const [pattern, fn] of ctx.hooks) {
     if (pattern.test(path)) {
-      const output = await fn(input);
+      const output = await fn(input, ctx);
 
       if (output !== void 0) {
         return output;
@@ -71,7 +71,9 @@ async function _process(input: unknown, hooks: Set<Hook>, path: string): Promise
 
   if (Array.isArray(input)) {
     return b.arrayExpression(
-      (await Promise.all(input.map((item, i) => _process(item, hooks, `${path}/${String(i)}`)))).filter(Boolean),
+      (await Promise.all(input.map(async (item, i) => await _process(item, ctx, `${path}/${String(i)}`)))).filter(
+        Boolean,
+      ),
     );
   } else if (typeof input === 'number' || typeof input === 'boolean' || typeof input === 'string') {
     return b.literal(input);
@@ -87,7 +89,7 @@ async function _process(input: unknown, hooks: Set<Hook>, path: string): Promise
     (
       await Promise.all(
         Object.entries(input).map(async ([key, value]) => {
-          const propertyValue = await _process(value, hooks, `${path}/${key}`);
+          const propertyValue = await _process(value, ctx, `${path}/${key}`);
 
           if (propertyValue !== null) {
             return b.property('init', b.identifier(JSON.stringify(key)), propertyValue);
@@ -100,6 +102,6 @@ async function _process(input: unknown, hooks: Set<Hook>, path: string): Promise
   );
 }
 
-export async function process(input: Ruleset, hooks: Set<Hook>): Promise<namedTypes.ObjectExpression> {
-  return (await _process(input, hooks, '')) as namedTypes.ObjectExpression;
+export async function process(input: Ruleset, ctx: TransformerCtx): Promise<namedTypes.ObjectExpression> {
+  return (await _process(input, ctx, '')) as namedTypes.ObjectExpression;
 }
diff --git a/packages/ruleset-migrator/src/transformers/except.ts b/packages/ruleset-migrator/src/transformers/except.ts
index f5db9a90be..933c0552ea 100644
--- a/packages/ruleset-migrator/src/transformers/except.ts
+++ b/packages/ruleset-migrator/src/transformers/except.ts
@@ -3,27 +3,24 @@ import { Ruleset } from '../validation/types';
 
 export { transformer as default };
 
-const transformer: Transformer = function (ctx) {
-  ctx.hooks.add([
-    /^$/,
-    (_ruleset): void => {
-      const ruleset = _ruleset as Ruleset;
-      const { except } = ruleset;
+const transformer: Transformer = function (registerHook) {
+  registerHook(/^$/, (_ruleset): void => {
+    const ruleset = _ruleset as Ruleset;
+    const { except } = ruleset;
 
-      if (except === void 0) return;
+    if (except === void 0) return;
 
-      delete ruleset.except;
+    delete ruleset.except;
 
-      const overrides = (ruleset.overrides ??= []) as unknown[];
-      overrides.push(
-        ...Object.keys(except).map(pattern => ({
-          files: [pattern.startsWith('#') ? `**${pattern}` : pattern],
-          rules: except[pattern].reduce((rules, rule) => {
-            rules[rule] = 'off';
-            return rules;
-          }, {}),
-        })),
-      );
-    },
-  ]);
+    const overrides = (ruleset.overrides ??= []) as unknown[];
+    overrides.push(
+      ...Object.keys(except).map(pattern => ({
+        files: [pattern.startsWith('#') ? `**${pattern}` : pattern],
+        rules: except[pattern].reduce((rules, rule) => {
+          rules[rule] = 'off';
+          return rules;
+        }, {}),
+      })),
+    );
+  });
 };
diff --git a/packages/ruleset-migrator/src/transformers/extends.ts b/packages/ruleset-migrator/src/transformers/extends.ts
index 2479f6cd0f..22fa9b93b8 100644
--- a/packages/ruleset-migrator/src/transformers/extends.ts
+++ b/packages/ruleset-migrator/src/transformers/extends.ts
@@ -22,28 +22,23 @@ async function processExtend(
     return ctx.tree.addImport(REPLACEMENTS[name], '@stoplight/spectral-rulesets');
   }
 
-  const existingCwd = ctx.cwd;
-  const filepath = ctx.tree.resolveModule(name, existingCwd);
+  const filepath = ctx.tree.resolveModule(name, ctx.cwd);
 
   if (KNOWN_JS_EXTS.test(path.extname(filepath))) {
     return ctx.tree.addImport(`${path.basename(filepath, true)}_${path.extname(filepath)}`, filepath, true);
   }
 
-  const scope = ctx.tree.scope;
-  try {
-    ctx.cwd = path.dirname(filepath);
-    ctx.tree.scope = ctx.tree.scope.fork();
-    return await process(await ctx.read(filepath, ctx.opts.fs, ctx.opts.fetch), ctx.hooks);
-  } finally {
-    ctx.tree.scope = scope;
-    ctx.cwd = existingCwd;
-  }
+  return await process(await ctx.read(filepath, ctx.opts.fs, ctx.opts.fetch), {
+    ...ctx,
+    cwd: path.dirname(filepath),
+    tree: ctx.tree.fork(),
+  });
 }
 
-const transformer: Transformer = function (ctx) {
-  ctx.hooks.add([
+const transformer: Transformer = function (registerHook) {
+  registerHook(
     /^(\/overrides\/\d+)?\/extends$/,
-    async (input): Promise<namedTypes.ArrayExpression | namedTypes.ObjectExpression | namedTypes.Identifier> => {
+    async (input, ctx): Promise<namedTypes.ArrayExpression | namedTypes.ObjectExpression | namedTypes.Identifier> => {
       const _extends = input as Ruleset['extends'];
 
       if (typeof _extends === 'string') {
@@ -63,5 +58,5 @@ const transformer: Transformer = function (ctx) {
 
       return b.arrayExpression(extendedRulesets);
     },
-  ]);
+  );
 };
diff --git a/packages/ruleset-migrator/src/transformers/formats.ts b/packages/ruleset-migrator/src/transformers/formats.ts
index 8d7d86ec92..6beae50c36 100644
--- a/packages/ruleset-migrator/src/transformers/formats.ts
+++ b/packages/ruleset-migrator/src/transformers/formats.ts
@@ -18,7 +18,7 @@ const REPLACEMENTS = Object.fromEntries(
   ]),
 );
 
-function transform(ctx: TransformerCtx, input: unknown): namedTypes.ArrayExpression {
+function transform(input: unknown, ctx: TransformerCtx): namedTypes.ArrayExpression {
   assertArray(input);
 
   return b.arrayExpression(
@@ -35,10 +35,8 @@ function transform(ctx: TransformerCtx, input: unknown): namedTypes.ArrayExpress
 
 export { transformer as default };
 
-const transformer: Transformer = function (ctx) {
-  const t = transform.bind(null, ctx);
-
-  ctx.hooks.add([/^\/aliases\/[^/]+\/targets\/\d+\/formats$/, t]);
-  ctx.hooks.add([/^(\/overrides\/\d+)?\/formats$/, t]);
-  ctx.hooks.add([/^(\/overrides\/\d+)?\/rules\/[^/]+\/formats$/, t]);
+const transformer: Transformer = function (registerHook) {
+  registerHook(/^\/aliases\/[^/]+\/targets\/\d+\/formats$/, transform);
+  registerHook(/^(\/overrides\/\d+)?\/formats$/, transform);
+  registerHook(/^(\/overrides\/\d+)?\/rules\/[^/]+\/formats$/, transform);
 };
diff --git a/packages/ruleset-migrator/src/transformers/functions.ts b/packages/ruleset-migrator/src/transformers/functions.ts
index fecfdc6a88..93f9adc3c1 100644
--- a/packages/ruleset-migrator/src/transformers/functions.ts
+++ b/packages/ruleset-migrator/src/transformers/functions.ts
@@ -5,35 +5,32 @@ import { Ruleset } from '../validation/types';
 
 export { transformer as default };
 
-const transformer: Transformer = function (ctx) {
-  ctx.hooks.add([
-    /^$/,
-    (_ruleset): void => {
-      const ruleset = _ruleset as Ruleset;
-      const { functionsDir, functions } = ruleset;
+const transformer: Transformer = function (registerHook) {
+  registerHook(/^$/, (_ruleset, ctx): void => {
+    const ruleset = _ruleset as Ruleset;
+    const { functionsDir, functions } = ruleset;
 
-      if (Array.isArray(functions) && functions.length > 0) {
-        ruleset.functions = functions.map(fn =>
-          ctx.tree.resolveModule(`${fn}.js`, path.join(ctx.cwd, functionsDir ?? 'functions')),
-        );
-        delete ruleset.functionsDir;
-      }
-    },
-  ]);
-
-  ctx.hooks.add([
-    /^\/functions$/,
-    (value): null => {
-      assertArray(value);
-
-      for (const fn of value) {
+    if (Array.isArray(functions) && functions.length > 0) {
+      for (const fn of functions) {
         assertString(fn);
-        const fnName = path.basename(fn, true);
-        const identifier = ctx.tree.addImport(fnName, fn, true);
+        const resolved = ctx.tree.resolveModule(
+          `${fn}.js`,
+          path.join(ctx.cwd, typeof functionsDir === 'string' ? functionsDir : 'functions'),
+        );
+        const fnName = path.basename(resolved, true);
+        const identifier = ctx.tree.addImport(fnName, resolved, true);
         ctx.tree.scope.store(`function-${fnName}`, identifier.name);
       }
+    }
+  });
+
+  registerHook(/^\/functions$/, (value): null => {
+    assertArray(value);
+    return null;
+  });
 
-      return null;
-    },
-  ]);
+  registerHook(/^\/functionsDir$/, (value): null => {
+    assertString(value);
+    return null;
+  });
 };
diff --git a/packages/ruleset-migrator/src/transformers/rules.ts b/packages/ruleset-migrator/src/transformers/rules.ts
index cdb739205c..1e3282c1fd 100644
--- a/packages/ruleset-migrator/src/transformers/rules.ts
+++ b/packages/ruleset-migrator/src/transformers/rules.ts
@@ -53,40 +53,37 @@ function getDiagnosticSeverity(severity: DiagnosticSeverity | string): Diagnosti
   return Number.isNaN(Number(severity)) ? SEVERITY_MAP[severity] : Number(severity);
 }
 
-const transformer: Transformer = function (ctx) {
-  ctx.hooks.add([
-    /^$/,
-    (_ruleset): void => {
-      const ruleset = _ruleset as Ruleset;
-      if (ruleset.rules === void 0) return;
-
-      const { rules } = ruleset;
-
-      // this is to make sure order of rules is preserved after transformation
-      ruleset.rules = createOrderedLiteral(rules);
-      const order = Object.keys(rules);
-
-      for (const [i, key] of order.entries()) {
-        if (!(key in REPLACEMENTS)) continue;
-        if (typeof rules[key] === 'object') continue; // we do not touch new definitions (aka custom rules). If one defines a rule like operation-2xx-response in their own ruleset, we shouldn't touch it.
-        const newName = REPLACEMENTS[key];
-        if (newName in rules) {
-          rules[newName] = max(String(rules[key]), String(rules[newName]));
-        } else {
-          rules[newName] ??= rules[key];
-        }
-
-        order[i] = newName;
-        delete rules[key];
+const transformer: Transformer = function (registerHook) {
+  registerHook(/^$/, (_ruleset): void => {
+    const ruleset = _ruleset as Ruleset;
+    if (ruleset.rules === void 0) return;
+
+    const { rules } = ruleset;
+
+    // this is to make sure order of rules is preserved after transformation
+    ruleset.rules = createOrderedLiteral(rules);
+    const order = Object.keys(rules);
+
+    for (const [i, key] of order.entries()) {
+      if (!(key in REPLACEMENTS)) continue;
+      if (typeof rules[key] === 'object') continue; // we do not touch new definitions (aka custom rules). If one defines a rule like operation-2xx-response in their own ruleset, we shouldn't touch it.
+      const newName = REPLACEMENTS[key];
+      if (newName in rules) {
+        rules[newName] = max(String(rules[key]), String(rules[newName]));
+      } else {
+        rules[newName] ??= rules[key];
       }
 
-      setOrder(rules, [...new Set([...order])]);
-    },
-  ]);
+      order[i] = newName;
+      delete rules[key];
+    }
+
+    setOrder(rules, [...new Set([...order])]);
+  });
 
-  ctx.hooks.add([
+  registerHook(
     /^\/rules\/[^/]+\/then\/(?:[0-9]+\/)?function$/,
-    (value): namedTypes.Identifier | namedTypes.UnaryExpression => {
+    (value, ctx): namedTypes.Identifier | namedTypes.UnaryExpression => {
       assertString(value);
 
       if (KNOWN_FUNCTIONS.includes(value)) {
@@ -96,5 +93,5 @@ const transformer: Transformer = function (ctx) {
       const alias = ctx.tree.scope.load(`function-${value}`);
       return alias !== void 0 ? b.identifier(alias) : b.unaryExpression('void', b.literal(0));
     },
-  ]);
+  );
 };
diff --git a/packages/ruleset-migrator/src/tree/index.ts b/packages/ruleset-migrator/src/tree/index.ts
index 3f8ac301b1..fddcd8ffb5 100644
--- a/packages/ruleset-migrator/src/tree/index.ts
+++ b/packages/ruleset-migrator/src/tree/index.ts
@@ -129,4 +129,22 @@ export class Tree {
 
     return resolved;
   }
+
+  public fork(): Tree {
+    const scope = this.scope.fork();
+    return new Proxy(this, {
+      get: (target, prop): Tree[keyof Tree] => {
+        if (prop === 'scope') {
+          return scope;
+        }
+
+        const value = Reflect.get(target, prop, target) as Tree[keyof Tree];
+        if (typeof value === 'function') {
+          return value.bind(target);
+        }
+
+        return value;
+      },
+    });
+  }
 }
diff --git a/packages/ruleset-migrator/src/types.ts b/packages/ruleset-migrator/src/types.ts
index 326f777274..d26e8ff96a 100644
--- a/packages/ruleset-migrator/src/types.ts
+++ b/packages/ruleset-migrator/src/types.ts
@@ -26,10 +26,10 @@ export type MigrationOptions = {
 
 export type Hook = [
   pattern: RegExp,
-  hook: (input: unknown) => Promise<ExpressionKind | null | void> | ExpressionKind | null | void,
+  hook: (input: unknown, ctx: TransformerCtx) => Promise<ExpressionKind | null | void> | ExpressionKind | null | void,
 ];
 
-export type Transformer = (ctx: TransformerCtx) => void;
+export type Transformer = (registerHook: (...params: Hook) => void) => void;
 
 export type TransformerCtx = {
   readonly tree: Tree;
diff --git a/yarn.lock b/yarn.lock
index 5dbe7866e3..729d2b5994 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1935,7 +1935,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@stoplight/json@npm:3.17.0, @stoplight/json@npm:^3.17.0, @stoplight/json@npm:~3.17.1":
+"@stoplight/json@npm:3.17.0, @stoplight/json@npm:^3.17.0, @stoplight/json@npm:~3.17.0, @stoplight/json@npm:~3.17.1":
   version: 3.17.0
   resolution: "@stoplight/json@npm:3.17.0"
   dependencies:
@@ -2129,7 +2129,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@stoplight/spectral-ruleset-migrator@workspace:packages/ruleset-migrator"
   dependencies:
-    "@stoplight/json": 3.17.0
+    "@stoplight/json": ~3.17.0
     "@stoplight/ordered-object-literal": 1.0.2
     "@stoplight/path": 1.3.2
     "@stoplight/spectral-core": ^1.1.0