diff --git a/packages/core/src/ruleset/rule.ts b/packages/core/src/ruleset/rule.ts
index 3cc581337..c0e2b6f83 100644
--- a/packages/core/src/ruleset/rule.ts
+++ b/packages/core/src/ruleset/rule.ts
@@ -11,6 +11,7 @@ import type { HumanReadableDiagnosticSeverity, IRuleThen, RuleDefinition, String
 import { minimatch } from './utils/minimatch';
 import { Formats } from './formats';
 import { resolveAlias } from './alias';
+import type { Stringified } from './types';
 
 export interface IRule {
   description: string | null;
@@ -25,13 +26,14 @@ export interface IRule {
   given: string[];
 }
 
-export type StringifiedRule = Omit<IRule, 'formats' | 'then'> & {
+type RuleJson = Omit<IRule, 'then'> & {
   name: string;
-  formats: string[] | null;
   then: (Pick<IRuleThen, 'field'> & { function: string; functionOptions?: string })[];
   owner: number;
 };
 
+export type StringifiedRule = Stringified<RuleJson>;
+
 export class Rule implements IRule {
   public description: string | null;
   public message: string | null;
@@ -164,7 +166,7 @@ export class Rule implements IRule {
     return new Rule(this.name, this.definition, this.owner);
   }
 
-  public toJSON(): Stringifable<StringifiedRule> {
+  public toJSON(): Stringifable<RuleJson> {
     return {
       name: this.name,
       recommended: this.recommended,
diff --git a/packages/core/src/ruleset/ruleset.ts b/packages/core/src/ruleset/ruleset.ts
index 87f11718a..4020b37e0 100644
--- a/packages/core/src/ruleset/ruleset.ts
+++ b/packages/core/src/ruleset/ruleset.ts
@@ -17,6 +17,7 @@ import { DEFAULT_PARSER_OPTIONS, getDiagnosticSeverity } from '..';
 import { mergeRulesets } from './mergers/rulesets';
 import { Formats } from './formats';
 import { isSimpleAliasDefinition } from './utils/guards';
+import type { Stringified } from './types';
 
 const STACK_SYMBOL = Symbol('@stoplight/spectral/ruleset/#stack');
 const DEFAULT_RULESET_FILE = /^\.?spectral\.(ya?ml|json|m?js)$/;
@@ -29,9 +30,9 @@ type RulesetContext = {
 
 let SEED = 1;
 
-export type StringifiedRuleset = {
+type RulesetJson = {
   id: number;
-  extends: StringifiedRuleset[] | null;
+  extends: RulesetJson[] | null;
   source: string | null;
   aliases: RulesetAliasesDefinition | null;
   formats: Formats | null;
@@ -40,6 +41,8 @@ export type StringifiedRuleset = {
   parserOptions: ParserOptions;
 };
 
+export type StringifiedRuleset = Stringified<RulesetJson>;
+
 export class Ruleset {
   public readonly id = SEED++;
 
@@ -309,7 +312,7 @@ export class Ruleset {
     return DEFAULT_RULESET_FILE.test(uri);
   }
 
-  public toJSON(): Stringifable<StringifiedRuleset> {
+  public toJSON(): Stringifable<RulesetJson> {
     return {
       id: this.id,
       extends: this.extends,
diff --git a/packages/core/src/ruleset/types.ts b/packages/core/src/ruleset/types.ts
index 381a18d10..e18e84b64 100644
--- a/packages/core/src/ruleset/types.ts
+++ b/packages/core/src/ruleset/types.ts
@@ -113,9 +113,14 @@ export type RulesetDefinition = Readonly<
   >
 >;
 
-// eslint-disable-next-line @typescript-eslint/ban-types
 export type Stringifable<T> = T extends object
   ? {
       [P in keyof T]: Stringifable<T[P]> | { toJSON?(): Stringifable<T[P]> };
     }
   : T;
+
+export type Stringified<T> = T extends object
+  ? {
+      [P in keyof T]: NonNullable<T[P]> extends { toJSON(): infer R } ? R : Stringified<T[P]>;
+    }
+  : T;