diff --git a/.nvmrc b/.nvmrc
new file mode 100644
index 0000000..b5045cc
--- /dev/null
+++ b/.nvmrc
@@ -0,0 +1 @@
+21
\ No newline at end of file
diff --git a/src/inject.js b/src/inject.js
index b6202f1..563399d 100644
--- a/src/inject.js
+++ b/src/inject.js
@@ -1,136 +1,6 @@
-import fs from "node:fs";
-import url from "node:url";
-import { parse } from "es-module-lexer";
-import { Parser } from "htmlparser2";
-import { resolve, parseFromString } from '@import-maps/resolve'
-
-async function getImports(script) {
-  const [imports] = await parse(script);
-  return imports.map((imp) => imp.n);
-}
-
-class ImportCollector {
-  constructor({ imports, baseUrl, importMap, noFetch }) {
-    this.imports = imports;
-    this.baseUrl = baseUrl;
-    this.dependencies = new Set();
-    this.noFetch = noFetch
-    this.importMap = importMap
-  }
-  async visit(specifier, parent) {
-    let resolvedImport = null
-    if (parent.protocol === "file:") {
-      const resolved = resolve(specifier, this.importMap, parent);
-      resolvedImport = resolved.resolvedImport
-      if (specifier.startsWith('/')) {
-        resolvedImport = new URL('.' + specifier, this.baseUrl)
-      }
-    } else if (parent.protocol.startsWith("http")) {
-      resolvedImport = new URL(specifier, parent.origin)
-    }
-    if (!resolvedImport) {
-      throw 'could not resolve import: ' + specifier
-    };
-    if (this.dependencies.has(resolvedImport.href)) return;
-    this.dependencies.add(resolvedImport.href);
-    if (resolvedImport.protocol === "file:") {
-      try {
-        const contents = await fs.promises.readFile(resolvedImport, "utf8");
-        const deps = await getImports(contents);
-        await Promise.all(
-          deps.map((dep) => this.visit(dep, resolvedImport))
-        );
-      } catch (e) {
-        console.warn('WARNING: could not read file: ' + resolvedImport.href + ' - skipping')
-      }
-    } else if (resolvedImport.protocol.startsWith("http")) {
-      if (!this.noFetch) {
-        const contents = await fetch(resolvedImport).then(res => res.text())
-        const deps = await getImports(contents);
-        await Promise.all(
-          deps.map((dep) => this.visit(dep, resolvedImport))
-        );
-      }
-    }
-  }
-  async collect() {
-    const parent = new URL('./index.js', this.baseUrl)
-    await Promise.all(this.imports.map((entry) => this.visit(entry, parent)));
-    return [...this.dependencies].map((dep) => dep.replace(this.baseUrl.href, "/"));
-  }
-}
-
-async function parseHtml(contents) {
-  const scripts = [];
-  let inScript = false;
-  let inImportMap = false;
-  let importMapString = ""
-  const parser = new Parser({
-    onopentag(name, attributes) {
-      if (name === "script" && attributes.type === "module") {
-        inScript = true;
-        scripts.unshift("");
-      }
-      if (name === "script" && attributes.type === "importmap") {
-        inImportMap = true;
-      }
-    },
-    ontext(text) {
-      if (inScript) {
-        scripts[0] += text;
-      }
-      if (inImportMap) {
-        importMapString += text;
-      }
-    },
-    onclosetag(tagname) {
-      if (tagname === "script") {
-        inScript = false;
-        inImportMap = false;
-      }
-    },
-  });
-  parser.write(contents);
-  parser.end();
-  const imports = new Set()
-  for (let script of scripts) {
-    const deps = await getImports(script);
-    deps.forEach((d) => imports.add(d));
-  }
-  return { imports: [...imports], importMapString: importMapString || '{}' };
-}
-
-export async function getDependencies(contents, baseUrl, { noFetch } = {}) {
-  if (!baseUrl) {
-    throw new Error('baseUrl is required')
-  }
-  if (!baseUrl.href.endsWith('/')) {
-    baseUrl.href += '/'
-  }
-  const { importMapString, imports } = await parseHtml(contents);
-  const importMap = parseFromString(importMapString, baseUrl);
-  const collector = new ImportCollector({ imports, baseUrl, importMap, noFetch });
-  return collector.collect();
-}
-
-export function injectPreloads(contents, dependencies) {
-  let preloads = "";
-  for (const dep of dependencies) {
-    preloads += `<link rel="modulepreload" href="${dep}" />\n`;
-  }
-  return contents.replace("</head>", `${preloads}</head>`);
-}
-
-export async function link(htmlContentsOrUrl, { baseUrl: providedBaseUrl, noFetch } = {}) {
-  let html = htmlContentsOrUrl;
-  let baseUrl = providedBaseUrl;
-  if (htmlContentsOrUrl instanceof URL) {
-    html = await fs.promises.readFile(htmlContentsOrUrl, "utf8");
-    baseUrl = new URL('./', htmlContentsOrUrl)
-  }
-  const dependencies = await getDependencies(html, baseUrl, { noFetch });
-  return injectPreloads(html, dependencies);
-}
+import fs from 'node:fs'
+import url from 'node:url'
+import link from './link.js'
 
 export async function inject(htmlPath, { out, root, noFetch } = {}) {
   const htmlUrl = url.pathToFileURL(htmlPath)
diff --git a/src/link.js b/src/link.js
new file mode 100644
index 0000000..6d21bb0
--- /dev/null
+++ b/src/link.js
@@ -0,0 +1,145 @@
+import fs from "node:fs";
+import url from "node:url";
+import { parse } from "es-module-lexer";
+import { Parser } from "htmlparser2";
+import { resolve, parseFromString } from '@import-maps/resolve'
+
+async function getImports(script) {
+  const [imports] = await parse(script);
+  return imports.map((imp) => imp.n);
+}
+
+class ImportCollector {
+  constructor({ imports, baseUrl, importMap, noFetch }) {
+    this.imports = imports;
+    this.baseUrl = baseUrl;
+    this.dependencies = new Set();
+    this.noFetch = noFetch
+    this.importMap = importMap
+  }
+  async visit(specifier, parent) {
+    let resolvedImport = null
+    if (parent.protocol === "file:") {
+      const resolved = resolve(specifier, this.importMap, parent);
+      resolvedImport = resolved.resolvedImport
+      if (specifier.startsWith('/')) {
+        resolvedImport = new URL('.' + specifier, this.baseUrl)
+      }
+    } else if (parent.protocol.startsWith("http")) {
+      resolvedImport = new URL(specifier, parent.origin)
+    }
+    if (!resolvedImport) {
+      console.warn(`WARNING: could not resolve import specifier: ${specifier} from parent: ${parent} - skipping`)
+      return
+    };
+    if (this.dependencies.has(resolvedImport.href)) return;
+    this.dependencies.add(resolvedImport.href);
+    if (resolvedImport.protocol === "file:") {
+      let contents = null
+      try {
+        contents = await fs.promises.readFile(resolvedImport, "utf8");
+      } catch (e) {
+        console.warn('WARNING: could not read file: ' + resolvedImport.href + ' - skipping')
+      }
+      if (contents) {
+        const deps = await getImports(contents);
+        await Promise.all(
+          deps.map((dep) => this.visit(dep, resolvedImport))
+        );
+      }
+      // console.error(e)
+    } else if (resolvedImport.protocol.startsWith("http")) {
+      if (!this.noFetch) {
+        const contents = await fetch(resolvedImport).then(res => res.text())
+        const deps = await getImports(contents);
+        await Promise.all(
+          deps.map((dep) => this.visit(dep, resolvedImport))
+        );
+      }
+    }
+  }
+  async collect() {
+    const parent = new URL('./index.js', this.baseUrl)
+    await Promise.all(this.imports.map((entry) => this.visit(entry, parent)));
+    return [...this.dependencies].map((dep) => dep.replace(this.baseUrl.href, "/"));
+  }
+}
+
+async function parseHtml(contents) {
+  const scripts = [];
+  let inScript = false;
+  let inImportMap = false;
+  let importMapString = ""
+  const parser = new Parser({
+    onopentag(name, attributes) {
+      if (name === "script" && attributes.type === "module") {
+        inScript = true;
+        scripts.unshift("");
+      }
+      if (name === "script" && attributes.type === "importmap") {
+        inImportMap = true;
+      }
+    },
+    ontext(text) {
+      if (inScript) {
+        scripts[0] += text;
+      }
+      if (inImportMap) {
+        importMapString += text;
+      }
+    },
+    onclosetag(tagname) {
+      if (tagname === "script") {
+        inScript = false;
+        inImportMap = false;
+      }
+    },
+  });
+  parser.write(contents);
+  parser.end();
+  const imports = new Set()
+  for (let script of scripts) {
+    const deps = await getImports(script);
+    deps.forEach((d) => imports.add(d));
+  }
+  return { imports: [...imports], importMapString: importMapString || '{}' };
+}
+
+export async function getDependencies(contents, baseUrl, { noFetch } = {}) {
+  if (!baseUrl) {
+    throw new Error('baseUrl is required')
+  }
+  if (!baseUrl.href.endsWith('/')) {
+    baseUrl.href += '/'
+  }
+  const { importMapString, imports } = await parseHtml(contents);
+  const importMap = parseFromString(importMapString, baseUrl);
+  const collector = new ImportCollector({ imports, baseUrl, importMap, noFetch });
+  return collector.collect();
+}
+
+export function injectPreloads(contents, dependencies) {
+  let preloads = "";
+  for (const dep of dependencies) {
+    preloads += `<link rel="modulepreload" href="${dep}" />\n`;
+  }
+  if (contents.includes("</head>")) {
+    return contents.replace("</head>", `${preloads}</head>`);
+  } else if (contents.includes("</html>")) {
+    return contents.replace("<html>", `<html>\n${preloads}`);
+  } else {
+    console.warn('WARNING: could not find <head> or <html> in HTML - skipping.')
+    return contents;
+  }
+}
+
+export default async function link(htmlContentsOrUrl, { baseUrl: providedBaseUrl, noFetch } = {}) {
+  let html = htmlContentsOrUrl;
+  let baseUrl = providedBaseUrl;
+  if (htmlContentsOrUrl instanceof URL) {
+    html = await fs.promises.readFile(htmlContentsOrUrl, "utf8");
+    baseUrl = new URL('./', htmlContentsOrUrl)
+  }
+  const dependencies = await getDependencies(html, baseUrl, { noFetch });
+  return injectPreloads(html, dependencies);
+}
diff --git a/tests/fixtures/absolute-dep.js b/tests/fixtures/link/absolute-dep.js
similarity index 100%
rename from tests/fixtures/absolute-dep.js
rename to tests/fixtures/link/absolute-dep.js
diff --git a/tests/fixtures/index.html b/tests/fixtures/link/index.html
similarity index 100%
rename from tests/fixtures/index.html
rename to tests/fixtures/link/index.html
diff --git a/tests/fixtures/js/dep.js b/tests/fixtures/link/js/dep.js
similarity index 100%
rename from tests/fixtures/js/dep.js
rename to tests/fixtures/link/js/dep.js
diff --git a/tests/fixtures/js/secondary-dep.js b/tests/fixtures/link/js/secondary-dep.js
similarity index 100%
rename from tests/fixtures/js/secondary-dep.js
rename to tests/fixtures/link/js/secondary-dep.js
diff --git a/tests/fixtures/link/no-head.html b/tests/fixtures/link/no-head.html
new file mode 100644
index 0000000..d764bc7
--- /dev/null
+++ b/tests/fixtures/link/no-head.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html>
+
+<body>
+    <h1>Hello, world!</h1>
+</body>
+<script type="module">
+    import { hello } from './absolute-dep.js';
+</script>
+
+</html>
\ No newline at end of file
diff --git a/tests/inject.test.js b/tests/inject.test.js
deleted file mode 100644
index 9cafbf4..0000000
--- a/tests/inject.test.js
+++ /dev/null
@@ -1,7 +0,0 @@
-import { link } from '../src/inject.js';
-import test from 'node:test';
-
-test('inject', async (t) => {
-    const htmlUrl = new URL('./fixtures/index.html', import.meta.url)
-    console.log(await link(htmlUrl, { noFetch: true }))
-});
diff --git a/tests/link.test.js b/tests/link.test.js
new file mode 100644
index 0000000..ee8bcab
--- /dev/null
+++ b/tests/link.test.js
@@ -0,0 +1,19 @@
+import link from '../src/link.js';
+import { describe, it } from 'node:test';
+import fs from 'node:fs';
+import assert from 'node:assert';
+
+describe('link', () => {
+    it('injects dependencies into HTML', async () => {
+        const htmlUrl = new URL('./fixtures/link/index.html', import.meta.url)
+        const result = await link(htmlUrl, { noFetch: true })
+        const expected = await fs.promises.readFile(new URL('./snapshots/link/index.snapshot.html', import.meta.url), 'utf8')
+        assert.strictEqual(result, expected)
+    })
+    it('injects dependencies to top of <html> if there is no <head> tag', async () => {
+        const htmlUrl = new URL('./fixtures/link/no-head.html', import.meta.url)
+        const result = await link(htmlUrl, { noFetch: true })
+        const expected = await fs.promises.readFile(new URL('./snapshots/link/no-head.snapshot.html', import.meta.url), 'utf8')
+        assert.strictEqual(result, expected)
+    });
+})
diff --git a/tests/snapshots/link/index.snapshot.html b/tests/snapshots/link/index.snapshot.html
new file mode 100644
index 0000000..6169a9f
--- /dev/null
+++ b/tests/snapshots/link/index.snapshot.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<html>
+
+<head>
+    <title>My HTML File</title>
+    <script type="importmap">
+        {
+            "imports": {
+                "jquery": "https://cdn.skypack.dev/jquery"
+            }
+        }
+    </script>
+<link rel="modulepreload" href="/js/dep.js" />
+<link rel="modulepreload" href="/js/secondary-dep.js" />
+<link rel="modulepreload" href="/absolute-dep.js" />
+<link rel="modulepreload" href="https://cdn.skypack.dev/jquery" />
+</head>
+
+<body>
+    <h1>Hello, world!</h1>
+</body>
+<script type="module">
+    import { hello } from './js/dep.js';
+</script>
+
+</html>
\ No newline at end of file
diff --git a/tests/snapshots/link/no-head.snapshot.html b/tests/snapshots/link/no-head.snapshot.html
new file mode 100644
index 0000000..81e5156
--- /dev/null
+++ b/tests/snapshots/link/no-head.snapshot.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<html>
+<link rel="modulepreload" href="/absolute-dep.js" />
+
+
+<body>
+    <h1>Hello, world!</h1>
+</body>
+<script type="module">
+    import { hello } from './absolute-dep.js';
+</script>
+
+</html>
\ No newline at end of file