diff --git a/index.ts b/index.ts
index 77e563e..c813a84 100644
--- a/index.ts
+++ b/index.ts
@@ -1,6 +1,13 @@
-import {createFilter} from '@rollup/pluginutils';
+import { createFilter } from '@rollup/pluginutils';
+import type {
+  ArrowFunctionExpression,
+  Identifier,
+  Literal,
+  Node,
+  TemplateLiteral,
+} from 'estree';
 import * as transformAst from 'transform-ast';
-import {PluginOption} from 'vite';
+import { PluginOption } from 'vite';
 
 interface PostcssLitOptions {
   /**
@@ -27,18 +34,19 @@ interface PostcssLitOptions {
   importPackage?: string;
 }
 
-const escape = (str: string): string => str
-  .replace(/`/g, '\\`')
-  .replace(/\\(?!`)/g, '\\\\');
+const CSS_TAG = 'cssTag';
+
+const escape = (str: string): string =>
+  str.replace(/`/g, '\\`').replace(/\\(?!`)/g, '\\\\');
 
 export = function postcssLit(options: PostcssLitOptions = {}): PluginOption {
   const defaultOptions: PostcssLitOptions = {
     include: '**/*.{css,sss,pcss,styl,stylus,sass,scss,less}?(*)',
-    exclude: '**/*\?direct*',
+    exclude: '**/*?direct*',
     importPackage: 'lit',
   };
 
-  const opts: PostcssLitOptions = {...defaultOptions, ...options};
+  const opts: PostcssLitOptions = { ...defaultOptions, ...options };
   const filter = createFilter(opts.include, opts.exclude);
 
   return {
@@ -47,37 +55,75 @@ export = function postcssLit(options: PostcssLitOptions = {}): PluginOption {
     transform(code, id) {
       if (!filter(id)) return;
       const ast = this.parse(code, {});
-      // export default const css;
-      let defaultExportName;
-
-      // export default '...';
-      let isDeclarationLiteral = false;
-      const magicString = transformAst(code, {ast: ast},
-        node => {
-          if (node.type === 'ExportDefaultDeclaration') {
-            defaultExportName = node.declaration.name;
 
-            isDeclarationLiteral = node.declaration.type === 'Literal';
-          }
-        },
-      );
+      let defaultExportName: string;
+      let cssStringNode: Literal | TemplateLiteral;
+      const magicString = transformAst(code, { ast: ast });
 
-      if (!defaultExportName && !isDeclarationLiteral) {
-        return;
-      }
-      magicString.walk(node => {
-        if (defaultExportName && node.type === 'VariableDeclaration') {
-          const exportedVar = node.declarations.find(d => d.id.name === defaultExportName);
-          if (exportedVar) {
-            exportedVar.init.edit.update(`cssTag\`${escape(exportedVar.init.value)}\``);
+      magicString.walk((node: Node) => {
+        if (node.type === 'ExportDefaultDeclaration') {
+          switch (node.declaration.type) {
+            case 'Literal': // export default '...';
+            case 'TemplateLiteral': // export default `...`;
+              cssStringNode = node.declaration;
+              break;
+            case 'Identifier': // const css = '...'; export default css;
+              defaultExportName = node.declaration.name;
+              break;
+            case 'CallExpression': {
+              // export default (() => '...')();
+              const arrowFunctionBody = (
+                node.declaration.callee as ArrowFunctionExpression
+              ).body;
+              if (
+                arrowFunctionBody.type === 'Literal' ||
+                arrowFunctionBody.type === 'TemplateLiteral'
+              ) {
+                cssStringNode = arrowFunctionBody;
+              }
+              break;
+            }
+            default:
           }
         }
+      });
 
-        if (isDeclarationLiteral && node.type === 'ExportDefaultDeclaration') {
-          node.declaration.edit.update(`cssTag\`${escape(node.declaration.value)}\``)
+      if (!cssStringNode) {
+        if (!defaultExportName) {
+          this.warn(`Unrecognized default export in file ${id}`);
+          return;
         }
-      });
-      magicString.prepend(`import {css as cssTag} from '${opts.importPackage}';\n`);
+        magicString.walk((node: Node) => {
+          if (node.type === 'VariableDeclaration') {
+            const exportedVar = node.declarations.find(
+              d =>
+                (d.id as Identifier)?.name === defaultExportName &&
+                (d.init?.type === 'Literal' ||
+                  d.init?.type === 'TemplateLiteral'),
+            );
+            if (exportedVar) {
+              cssStringNode = exportedVar.init as typeof cssStringNode;
+            }
+          }
+        });
+      }
+
+      if (!cssStringNode) {
+        return this.error(`Unrecognized export expression in file ${id}`);
+      }
+
+      if (cssStringNode.type === 'Literal') {
+        cssStringNode.edit.update(
+          `${CSS_TAG}\`${escape(cssStringNode.value as string)}\``,
+        );
+      } else {
+        cssStringNode.edit.prepend(CSS_TAG);
+      }
+
+      magicString.prepend(
+        `import {css as ${CSS_TAG}} from '${opts.importPackage}';\n`,
+      );
+
       return {
         code: magicString.toString(),
         map: magicString.generateMap({
diff --git a/package.json b/package.json
index 12c1beb..6d49cc8 100644
--- a/package.json
+++ b/package.json
@@ -34,6 +34,8 @@
   },
   "homepage": "https://github.com/umbopepato/rollup-plugin-postcss-lit#readme",
   "devDependencies": {
+    "@types/estree": "^1.0.1",
+    "glob": "^10.2.7",
     "@types/mocha": "^10.0.1",
     "@types/node": "^18.16.1",
     "jsdom": "^22.1.0",
diff --git a/test/entry-literal.mjs b/test/entry-literal.mjs
deleted file mode 100644
index 1d95474..0000000
--- a/test/entry-literal.mjs
+++ /dev/null
@@ -1,2 +0,0 @@
-import test from './test-literal.mjs';
-export default test;
diff --git a/test/entry.mjs b/test/entry.mjs
index 608d9fb..a96ced5 100644
--- a/test/entry.mjs
+++ b/test/entry.mjs
@@ -1,2 +1,3 @@
 import test from './test.css';
-export default test;
\ No newline at end of file
+
+export default test;
diff --git a/test/intermediate-iife.mjs b/test/intermediate-iife.mjs
new file mode 100644
index 0000000..7f05a16
--- /dev/null
+++ b/test/intermediate-iife.mjs
@@ -0,0 +1,2 @@
+export default (() =>
+  '.test {\n    color: white;\n    background: url("./test.jpg");\n}\n\n.test:after {\n    content: "\\2014";\n}\n')();
diff --git a/test/intermediate-literal.mjs b/test/intermediate-literal.mjs
new file mode 100644
index 0000000..64a736c
--- /dev/null
+++ b/test/intermediate-literal.mjs
@@ -0,0 +1 @@
+export default '.test {\n    color: white;\n    background: url("./test.jpg");\n}\n\n.test:after {\n    content: "\\2014";\n}\n';
diff --git a/test/intermediate-template-var.mjs b/test/intermediate-template-var.mjs
new file mode 100644
index 0000000..7c36329
--- /dev/null
+++ b/test/intermediate-template-var.mjs
@@ -0,0 +1,3 @@
+const css = `.test {\n    color: white;\n    background: url("./test.jpg");\n}\n\n.test:after {\n    content: "\\2014";\n}\n`;
+
+export default css;
diff --git a/test/intermediate-template.mjs b/test/intermediate-template.mjs
new file mode 100644
index 0000000..ec279c7
--- /dev/null
+++ b/test/intermediate-template.mjs
@@ -0,0 +1 @@
+export default `.test {\n    color: white;\n    background: url("./test.jpg");\n}\n\n.test:after {\n    content: "\\2014";\n}\n`;
diff --git a/test/test-literal.mjs b/test/test-literal.mjs
deleted file mode 100644
index 1a8f69b..0000000
--- a/test/test-literal.mjs
+++ /dev/null
@@ -1 +0,0 @@
-export default ".test {\n    color: white;\n    background: url(\"./test.jpg\");\n}\n\n.test:after {\n    content: \"\\2014\";\n}\n";
diff --git a/test/test.spec.mjs b/test/test.spec.mjs
index 6688e7a..6322a9f 100644
--- a/test/test.spec.mjs
+++ b/test/test.spec.mjs
@@ -1,69 +1,91 @@
-import {readFileSync} from 'fs';
-import postcss from 'rollup-plugin-postcss';
+import virtual from '@rollup/plugin-virtual';
+import { strict as assert } from 'assert';
+import { readFileSync, rmSync } from 'fs';
+import { globSync } from 'glob';
+import { CSSResult } from 'lit';
 import * as rollup from 'rollup';
-import {CSSResult} from 'lit';
-import {strict as assert} from 'assert';
+import postcss from 'rollup-plugin-postcss';
 import postcssLit from '../dist/index.js';
 
 const cssFile = './test/test.css';
 const entry = './test/entry.mjs';
-const readFile = (path) => readFileSync(path, 'utf-8');
+const readFile = path => readFileSync(path, 'utf-8');
 
 describe('rollup-plugin-postcss-lit', () => {
-    it('should wrap an exported style string in the css template literal tag', async () => {
-        const outFile = 'out.mjs';
-        const cssText = readFile(cssFile);
-        await renderFile(entry, `./test/${outFile}`,[
-            postcss({
-                inject: false,
-            }),
-            postcssLit(),
-        ]);
-        const litStyle = await import(`./${outFile}`).then(m => m.default);
-        assert.ok(litStyle instanceof CSSResult);
-        assert.equal(litStyle.cssText, cssText);
+  it('should wrap an exported style string in the css template literal tag', async () => {
+    const outFile = 'out.mjs';
+    const cssText = readFile(cssFile);
+    await renderFile(entry, `./test/${outFile}`, [
+      postcss({
+        inject: false,
+      }),
+      postcssLit(),
+    ]);
+    const litStyle = await import(`./${outFile}`).then(m => m.default);
+    assert.ok(litStyle instanceof CSSResult);
+    assert.equal(litStyle.cssText, cssText);
 
-        const outFileText = readFile(`./test/${outFile}`);
-        const hasLitImport = outFileText.includes(`from 'lit';`);
-        assert.ok(hasLitImport);
-    });
+    const outFileText = readFile(`./test/${outFile}`);
+    const hasLitImport = outFileText.includes(`from 'lit';`);
+    assert.ok(hasLitImport);
+  });
 
-    it('should wrap a default export literal', async () => {
-        const outFile = 'out-literal.mjs';
-        const intermediateFile = 'test-literal.mjs';
-        await renderFile('./test/entry-literal.mjs', `./test/${outFile}`,[
-            postcssLit({ include: `**/${intermediateFile}` }),
-        ]);
-        const cssText = await import(`./${intermediateFile}`).then(m => m.default);
-        const litStyle = await import(`./${outFile}`).then(m => m.default);
-        assert.ok(litStyle instanceof CSSResult);
-        assert.equal(litStyle.cssText, cssText);
-    });
+  it('should support different export expressions', async () => {
+    for (const intermediateFile of globSync('./intermediate-?(*).mjs', {
+      cwd: './test',
+    })) {
+      const outFile = intermediateFile.replace('intermediate', 'out');
+      const input = 'virtual-entry.mjs';
+      const bundle = await rollup.rollup({
+        input,
+        plugins: [
+          virtual({
+            [input]: `import test from './test/${intermediateFile}'; export default test;`,
+          }),
+          postcssLit({ include: `**/${intermediateFile}` }),
+        ],
+      });
+      await bundle.write({
+        file: `./test/${outFile}`,
+        format: 'es',
+      });
+      const cssText = await import(`./${intermediateFile}`).then(
+        m => m.default,
+      );
+      const litStyle = await import(`./${outFile}`).then(m => m.default);
+      assert.ok(litStyle instanceof CSSResult);
+      assert.equal(litStyle.cssText, cssText);
+    }
+  });
 
-    it('can accept a different import package', async () => {
-        const outFile = './test/out-import.mjs';
-        await renderFile(entry, outFile,[
-            postcss({
-                inject: false,
-            }),
-            postcssLit({
-                importPackage: 'lit-element',
-            }),
-        ]);
+  it('can accept a different import package', async () => {
+    const outFile = './test/out-import.mjs';
+    await renderFile(entry, outFile, [
+      postcss({
+        inject: false,
+      }),
+      postcssLit({
+        importPackage: 'lit-element',
+      }),
+    ]);
 
-        const outFileText = readFile(outFile);
-        const hasLitElementImport = outFileText.includes(`from 'lit-element';`);
-        assert.ok(hasLitElementImport);
-    });
+    const outFileText = readFile(outFile);
+    const hasLitElementImport = outFileText.includes(`from 'lit-element';`);
+    assert.ok(hasLitElementImport);
+  });
+
+  after(() => {
+    globSync('./test/out*').forEach(f => rmSync(f));
+  });
 });
 
 const renderFile = async (inFile, outFile, plugins) => {
-    const bundle = await rollup.rollup({
-        input: inFile,
-        plugins,
-    });
-    await bundle.write({
-        file: outFile,
-        format: 'es',
-    });
+  const bundle = await rollup.rollup({
+    input: inFile,
+    plugins,
+  });
+  await bundle.write({
+    file: outFile,
+    format: 'es',
+  });
 };
diff --git a/tsconfig.json b/tsconfig.json
index 22e1ea6..e5d2fc2 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -8,6 +8,5 @@
     "declaration": true,
     "skipLibCheck": true,
     "outDir": "dist"
-  },
-  "files": [ "index.ts"]
+  }
 }
diff --git a/types.d.ts b/types.d.ts
new file mode 100644
index 0000000..677faac
--- /dev/null
+++ b/types.d.ts
@@ -0,0 +1,12 @@
+import 'estree';
+
+declare module 'estree' {
+  export interface BaseNodeWithoutComments {
+    edit: {
+      source: () => string;
+      update: (replacement: string) => Node;
+      append: (append: string) => Node;
+      prepend: (prepend: string) => Node;
+    };
+  }
+}