diff --git a/js-api-doc/index.d.ts b/js-api-doc/index.d.ts
index 02cf87c4..ccf447ed 100644
--- a/js-api-doc/index.d.ts
+++ b/js-api-doc/index.d.ts
@@ -57,7 +57,7 @@ export {
   types,
 } from './legacy/function';
 export {
-  ImporterThis,
+  LegacyImporterThis,
   LegacyAsyncImporter,
   LegacySyncImporter,
   LegacyImporter,
@@ -68,7 +68,7 @@ export {
   LegacyStringOptions,
   LegacyOptions,
 } from './legacy/options';
-export {PluginThis} from './legacy/plugin_this';
+export {LegacyPluginThis} from './legacy/plugin_this';
 export {LegacyResult, render, renderSync} from './legacy/render';
 
 export const info: string;
diff --git a/js-api-doc/legacy/function.d.ts b/js-api-doc/legacy/function.d.ts
index 66d9f3aa..10739df0 100644
--- a/js-api-doc/legacy/function.d.ts
+++ b/js-api-doc/legacy/function.d.ts
@@ -1,12 +1,12 @@
-import {PluginThis} from './plugin_this';
+import {LegacyPluginThis} from './plugin_this';
 
 export type LegacySyncFunction = (
-  this: PluginThis,
+  this: LegacyPluginThis,
   ...args: LegacyValue[]
 ) => LegacyValue;
 
 export type LegacyAsyncFunction = (
-  this: PluginThis,
+  this: LegacyPluginThis,
   ...args: [...LegacyValue[], (type: LegacyValue) => void]
 ) => void;
 
diff --git a/js-api-doc/legacy/importer.d.ts b/js-api-doc/legacy/importer.d.ts
index 0a0e6f93..cfcca648 100644
--- a/js-api-doc/legacy/importer.d.ts
+++ b/js-api-doc/legacy/importer.d.ts
@@ -1,17 +1,17 @@
-import {PluginThis} from './plugin_this';
+import {LegacyPluginThis} from './plugin_this';
 
-interface ImporterThis extends PluginThis {
+interface LegacyImporterThis extends LegacyPluginThis {
   fromImport: boolean;
 }
 
 type LegacySyncImporter = (
-  this: ImporterThis,
+  this: LegacyImporterThis,
   url: string,
   prev: string
 ) => {file: string} | {contents: string};
 
 type LegacyAsyncImporter = (
-  this: ImporterThis,
+  this: LegacyImporterThis,
   url: string,
   prev: string,
   done: (data: {file: string} | {contents: string} | Error) => void
diff --git a/js-api-doc/legacy/plugin_this.d.ts b/js-api-doc/legacy/plugin_this.d.ts
index 407d1d50..12c41547 100644
--- a/js-api-doc/legacy/plugin_this.d.ts
+++ b/js-api-doc/legacy/plugin_this.d.ts
@@ -1,4 +1,4 @@
-export interface PluginThis {
+export interface LegacyPluginThis {
   options: {
     file?: string;
 
diff --git a/spec/js-api/index.d.ts b/spec/js-api/index.d.ts
index 2cec412e..5561b84a 100644
--- a/spec/js-api/index.d.ts
+++ b/spec/js-api/index.d.ts
@@ -79,7 +79,7 @@ export {
   types,
 } from './legacy/function';
 export {
-  ImporterThis,
+  LegacyImporterThis,
   LegacyAsyncImporter,
   LegacySyncImporter,
   LegacyImporter,
@@ -90,7 +90,7 @@ export {
   LegacyStringOptions,
   LegacyOptions,
 } from './legacy/options';
-export {PluginThis} from './legacy/plugin_this';
+export {LegacyPluginThis} from './legacy/plugin_this';
 export {LegacyResult, render, renderSync} from './legacy/render';
 
 /**
diff --git a/spec/js-api/legacy/function.d.ts b/spec/js-api/legacy/function.d.ts
index 66d9f3aa..10739df0 100644
--- a/spec/js-api/legacy/function.d.ts
+++ b/spec/js-api/legacy/function.d.ts
@@ -1,12 +1,12 @@
-import {PluginThis} from './plugin_this';
+import {LegacyPluginThis} from './plugin_this';
 
 export type LegacySyncFunction = (
-  this: PluginThis,
+  this: LegacyPluginThis,
   ...args: LegacyValue[]
 ) => LegacyValue;
 
 export type LegacyAsyncFunction = (
-  this: PluginThis,
+  this: LegacyPluginThis,
   ...args: [...LegacyValue[], (type: LegacyValue) => void]
 ) => void;
 
diff --git a/spec/js-api/legacy/importer.d.ts b/spec/js-api/legacy/importer.d.ts
index d0ecfe38..25363c31 100644
--- a/spec/js-api/legacy/importer.d.ts
+++ b/spec/js-api/legacy/importer.d.ts
@@ -1,10 +1,10 @@
-import {PluginThis} from './plugin_this';
+import {LegacyPluginThis} from './plugin_this';
 
 /**
  * The interface for the `this` keyword for custom importers. The implementation
  * must invoke importers with an appropriate `this`.
  */
-interface ImporterThis extends PluginThis {
+interface LegacyImporterThis extends LegacyPluginThis {
   /**
    * `true` if this importer invocation was caused by an `@import` statement and
    * `false` otherwise.
@@ -16,13 +16,13 @@ interface ImporterThis extends PluginThis {
 }
 
 type LegacySyncImporter = (
-  this: ImporterThis,
+  this: LegacyImporterThis,
   url: string,
   prev: string
 ) => {file: string} | {contents: string};
 
 type LegacyAsyncImporter = (
-  this: ImporterThis,
+  this: LegacyImporterThis,
   url: string,
   prev: string,
   done: (data: {file: string} | {contents: string} | Error) => void
diff --git a/spec/js-api/legacy/plugin_this.d.ts b/spec/js-api/legacy/plugin_this.d.ts
index 8aca937e..02230d7d 100644
--- a/spec/js-api/legacy/plugin_this.d.ts
+++ b/spec/js-api/legacy/plugin_this.d.ts
@@ -3,7 +3,7 @@
  * functions. The implementation must invoke importers and custom functions with
  * an appropriate `this`.
  */
-export interface PluginThis {
+export interface LegacyPluginThis {
   options: {
     /** The `file` option passed to the `render()` or `renderSync()` call. */
     file?: string;