diff --git a/README.md b/README.md
index ec8d7d1..32fb316 100644
--- a/README.md
+++ b/README.md
@@ -90,17 +90,6 @@ sass({
 });
 ```
 
-**Usage caveat:**
-
-There is a utility function that handles injecting individual style payloads into the page's head, which is output as `___$insertStyle` by the rollup-plugin-sass plugin.
-
-This function is output to `./dist/node_modules/...`, in user-land builds, so you have to make sure that it isn't
-ignored by your build tool(s) (E.g., rollup, webpack etc.); As a solution, you'll just have to make sure that the
-directory is "included"/not-"excluded" via your build tools facilities/added-plugins/etc.
-
-Additionally, if you're publishing an app to an internal registry, or similar, you'll have to
-make sure 'dist/node_modules' isn't ignored in this scenario as well.
-
 ### `processor`
 
 - Type: `Function`
diff --git a/package.json b/package.json
index 46be07b..38ffc3f 100644
--- a/package.json
+++ b/package.json
@@ -13,7 +13,7 @@
   },
   "scripts": {
     "prepare": "npm run build && npm test && husky",
-    "build": "npm run build-downlevel-dts && tsc --project tsconfig.build.plugin.json && tsc --project tsconfig.build.insertStyle.json",
+    "build": "npm run build-downlevel-dts && tsc --project tsconfig.build.json",
     "build-downlevel-dts": "node scripts/clean-and-run-downlevel-dts.js",
     "downlevel-dts": "downlevel-dts . ts3.5 [--to=3.5]",
     "test": "nyc --reporter=html --reporter=text ava && npm run test:rollup.config.spec.ts",
diff --git a/src/index.ts b/src/index.ts
index 5cc4989..7261e6a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -6,8 +6,6 @@ import * as fs from 'fs';
 import { createFilter } from '@rollup/pluginutils';
 import type {
   SassImporterResult,
-  RollupAssetInfo,
-  RollupChunkInfo,
   RollupPluginSassOptions,
   RollupPluginSassOutputFn,
   SassOptions,
@@ -15,6 +13,7 @@ import type {
   SassRenderResult,
 } from './types';
 import { isFunction, isObject, isString, warn } from './utils';
+import insertStyle from './insertStyle';
 
 // @note Rollup is added as a "devDependency" so no actual symbols should be imported.
 //  Interfaces and non-concrete types are ok.
@@ -26,13 +25,18 @@ type PluginState = {
 
   // "";  Used, currently to ensure that we're not pushing style objects representing
   // the same file-path into `pluginState.styles` more than once.
-  styleMaps: { [index: string]: { id?: string; content?: string } };
+  styleMaps: {
+    [index: string]: {
+      id?: string;
+      content?: string;
+    };
+  };
 };
 
 const MATCH_SASS_FILENAME_RE = /\.sass$/;
 const MATCH_NODE_MODULE_RE = /^~([a-z0-9]|@).+/i;
 
-const insertFnName = '___$insertStyle';
+const INSERT_STYLE_ID = '___$insertStyle';
 
 /**
  * Returns a sass `importer` list:
@@ -147,12 +151,11 @@ const processRenderResponse = (
 
         if (rollupOptions.insert) {
           /**
-           * Add `insertStyle` import for handling "inserting"
-           * *.css into *.html `head`.
-           * @see insertStyle.ts for additional information
+           * Include import using {@link INSERT_STYLE_ID} as source.
+           * It will be resolved to insert style function using `resolvedID` and `load` hooks
            */
-          imports = `import ${insertFnName} from '${__dirname}/insertStyle.js';\n`;
-          defaultExport = `${insertFnName}(${out});`;
+          imports = `import ${INSERT_STYLE_ID} from '${INSERT_STYLE_ID}';\n`;
+          defaultExport = `${INSERT_STYLE_ID}(${out});`;
         } else if (!rollupOptions.output) {
           defaultExport = out;
         }
@@ -178,13 +181,16 @@ export = function plugin(
     },
     options,
   );
+
   const {
     include = defaultIncludes,
     exclude = defaultExcludes,
     runtime: sassRuntime,
     options: incomingSassOptions = {} as SassOptions,
   } = pluginOptions;
+
   const filter = createFilter(include || '', exclude || '');
+
   const pluginState: PluginState = {
     styles: [],
     styleMaps: {},
@@ -193,7 +199,21 @@ export = function plugin(
   return {
     name: 'rollup-plugin-sass',
 
-    transform(code: string, filePath: string): Promise<any> {
+    /** @see https://rollupjs.org/plugin-development/#resolveid */
+    resolveId(source) {
+      if (source === INSERT_STYLE_ID) {
+        return INSERT_STYLE_ID;
+      }
+    },
+
+    /** @see https://rollupjs.org/plugin-development/#load */
+    load(id) {
+      if (id === INSERT_STYLE_ID) {
+        return `export default ${insertStyle.toString()}`;
+      }
+    },
+
+    transform(code, filePath) {
       if (!filter(filePath)) {
         return Promise.resolve();
       }
@@ -245,11 +265,7 @@ export = function plugin(
         ); // @note do not `catch` here - let error propagate to rollup level.
     },
 
-    generateBundle(
-      generateOptions: { file?: string },
-      bundle: { [fileName: string]: RollupAssetInfo | RollupChunkInfo },
-      isWrite: boolean,
-    ): Promise<any> {
+    generateBundle(generateOptions, _, isWrite) {
       if (
         !isWrite ||
         (!pluginOptions.insert &&
@@ -284,5 +300,5 @@ export = function plugin(
 
       return Promise.resolve(css);
     },
-  } as RollupPlugin;
+  };
 };
diff --git a/src/insertStyle.ts b/src/insertStyle.ts
index 1ac581d..1814aa0 100644
--- a/src/insertStyle.ts
+++ b/src/insertStyle.ts
@@ -1,10 +1,9 @@
 /**
  * Create a style tag and append to head tag
  *
- * @warning this file is not included directly in the source code!
- *          If user specifies inject option to true, an import to this file will be injected in rollup output.
- *          Due to this reason this file is compiled into a ESM module separated from other plugin source files.
- *          That is the reason of why there are two tsconfig.build files.
+ * @warning This function is injected inside rollup. According to this be sure
+ *          - to not include any side-effect
+ *          - do not import any library / other files content
  *
  * @return css style
  */
diff --git a/test/index.test.ts b/test/index.test.ts
index 6f9f9dc..9c45642 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -136,21 +136,6 @@ test('should support options.data', async (t) => {
 
 // #region insert option
 {
-  /**
-   * In unit tests we are targeting `src` folder,
-   * so there is no `insertStyle.js` file so `rollup` issues a warning
-   * that we can silence.
-   */
-  const onwarn: WarningHandlerWithDefault = (warning, defaultHandler) => {
-    if (
-      warning.code === 'UNRESOLVED_IMPORT' &&
-      warning.exporter?.includes('insertStyle.js')
-    ) {
-      return;
-    }
-    defaultHandler(warning);
-  };
-
   test('should insert CSS into head tag', async (t) => {
     const outputBundle = await rollup({
       input: 'test/fixtures/insert/index.js',
@@ -160,12 +145,46 @@ test('should support options.data', async (t) => {
           options: TEST_SASS_OPTIONS_DEFAULT,
         }),
       ],
-      onwarn,
     });
     const { output } = await outputBundle.generate(TEST_GENERATE_OPTIONS);
-    const result = getFirstChunkCode(output);
 
-    t.snapshot(result);
+    const outputFilePath = path.join(TEST_OUTPUT_DIR, 'insert-bundle');
+
+    await outputBundle.write({ dir: outputFilePath });
+
+    t.is(
+      output.length,
+      1,
+      'has 1 chunk (we are bundling all in one single file)',
+    );
+
+    const [{ moduleIds, modules }] = output;
+
+    t.is(
+      moduleIds.filter((it) => it.endsWith('insertStyle')).length,
+      1,
+      'include insertStyle one time',
+    );
+
+    const actualAModuleID = moduleIds.find((it) =>
+      it.endsWith('actual_a.scss'),
+    ) as string;
+    const actualAModule = modules[actualAModuleID];
+    t.truthy(actualAModule);
+    t.snapshot(
+      actualAModule.code,
+      'actual_a content is compiled with insertStyle',
+    );
+
+    const actualBModuleID = moduleIds.find((it) =>
+      it.endsWith('actual_b.scss'),
+    ) as string;
+    const actualBModule = modules[actualBModuleID];
+    t.truthy(actualBModule);
+    t.snapshot(
+      actualBModule.code,
+      'actual_b content is compiled with insertStyle',
+    );
   });
 
   test('should generate chunks with import insertStyle when `insert` is true', async (t) => {
@@ -180,26 +199,56 @@ test('should support options.data', async (t) => {
           options: TEST_SASS_OPTIONS_DEFAULT,
         }),
       ],
-      output: {
-        preserveModules: true,
-        preserveModulesRoot: 'src',
-      },
-      onwarn,
     });
 
-    const { output } = await outputBundle.generate(TEST_GENERATE_OPTIONS);
+    const { output } = await outputBundle.generate({
+      ...TEST_GENERATE_OPTIONS,
+      preserveModules: true,
+      preserveModulesRoot: 'src',
+    });
+
+    const outputFilePath = path.join(TEST_OUTPUT_DIR, 'insert-multiple-entry');
+
+    await outputBundle.write({
+      dir: outputFilePath,
+      preserveModules: true,
+      preserveModulesRoot: 'src',
+    });
+
+    t.is(output.length, 5, 'has 5 chunks');
+
+    const outputFileNames = output.map((it) => it.fileName);
+
+    t.is(
+      outputFileNames.filter((it) => it.startsWith('entry')).length,
+      2,
+      '1 chunk for each entry (2)',
+    );
+    t.is(
+      outputFileNames.filter((it) => it.startsWith('assets/actual')).length,
+      2,
+      '1 chunk for each entry style import (2)',
+    );
+    t.is(
+      outputFileNames.filter((it) => it.endsWith('insertStyle.js')).length,
+      1,
+      '1 chunk for insertStyle helper',
+    );
+
+    const styleFiles = output.filter((it) =>
+      it.fileName.startsWith('assets/actual'),
+    );
 
-    t.is(output.length, 2, 'has 2 chunks');
     t.true(
-      output.every((outputItem) => {
+      styleFiles.every((outputItem) => {
         if (outputItem.type === 'chunk') {
           const insertStyleImportsCount = outputItem.imports.filter((it) =>
-            it.includes('/insertStyle.js'),
+            it.endsWith('insertStyle.js'),
           ).length;
           return insertStyleImportsCount === 1;
         }
-        // if is an assets there is no need to check imports
-        return true;
+        // no asset should be present here
+        return false;
       }),
       'each chunk must include insertStyle once',
     );
diff --git a/test/snapshots/test/index.test.ts.md b/test/snapshots/test/index.test.ts.md
index 6a4cfab..50b26b9 100644
--- a/test/snapshots/test/index.test.ts.md
+++ b/test/snapshots/test/index.test.ts.md
@@ -63,14 +63,13 @@ Generated by [AVA](https://avajs.dev).
 
 ## should insert CSS into head tag
 
-> Snapshot 1
+> actual_a content is compiled with insertStyle
 
-    `import ___$insertStyle from '../../../src/insertStyle.js';␊
-    ␊
-    ___$insertStyle("body{color:red}");␊
-    ␊
-    ___$insertStyle("body{color:green}");␊
-    `
+    'insertStyle("body{color:red}");'
+
+> actual_b content is compiled with insertStyle
+
+    'insertStyle("body{color:green}");'
 
 ## should processor return as string
 
diff --git a/test/snapshots/test/index.test.ts.snap b/test/snapshots/test/index.test.ts.snap
index ad19319..bb19a59 100644
Binary files a/test/snapshots/test/index.test.ts.snap and b/test/snapshots/test/index.test.ts.snap differ
diff --git a/tsconfig.build.insertStyle.json b/tsconfig.build.insertStyle.json
deleted file mode 100644
index 94f6d05..0000000
--- a/tsconfig.build.insertStyle.json
+++ /dev/null
@@ -1,8 +0,0 @@
-/* @see insertStyle.ts for additional information */
-{
-  "extends": "./tsconfig.json",
-  "include": ["./src/insertStyle.ts"],
-  "compilerOptions": {
-    "module": "ES6"
-  }
-}
diff --git a/tsconfig.build.json b/tsconfig.build.json
new file mode 100644
index 0000000..3fa7686
--- /dev/null
+++ b/tsconfig.build.json
@@ -0,0 +1,4 @@
+{
+  "extends": "./tsconfig.json",
+  "include": ["./src/*"]
+}
diff --git a/tsconfig.build.plugin.json b/tsconfig.build.plugin.json
deleted file mode 100644
index e218d24..0000000
--- a/tsconfig.build.plugin.json
+++ /dev/null
@@ -1,6 +0,0 @@
-/* @see insertStyle.ts for additional information */
-{
-  "extends": "./tsconfig.json",
-  "include": ["./src/*"],
-  "exclude": ["./src/insertStyle.ts"]
-}