diff --git a/lib/src/utils.test.ts b/lib/src/utils.test.ts
new file mode 100644
index 00000000..0e7f29c7
--- /dev/null
+++ b/lib/src/utils.test.ts
@@ -0,0 +1,37 @@
+import {pathToFileURL} from 'url';
+import {pathToUrlString} from './utils';
+
+describe('utils', () => {
+  describe('pathToUrlString', () => {
+    it('encode relative path like `pathToFileURL`', () => {
+      const baseURL = pathToFileURL('').toString();
+      for (let i = 0; i < 128; i++) {
+        const char = String.fromCharCode(i);
+        const filename = `${i}-${char}`;
+        expect(pathToUrlString(filename)).toEqual(
+          pathToFileURL(filename)
+            .toString()
+            .slice(baseURL.length + 1)
+        );
+      }
+    });
+
+    it('encode percent encoded string like `pathToFileURL`', () => {
+      const baseURL = pathToFileURL('').toString();
+      for (let i = 0; i < 128; i++) {
+        const lowercase = `%${i < 10 ? '0' : ''}${i.toString(16)}`;
+        expect(pathToUrlString(lowercase)).toEqual(
+          pathToFileURL(lowercase)
+            .toString()
+            .slice(baseURL.length + 1)
+        );
+        const uppercase = lowercase.toUpperCase();
+        expect(pathToUrlString(uppercase)).toEqual(
+          pathToFileURL(uppercase)
+            .toString()
+            .slice(baseURL.length + 1)
+        );
+      }
+    });
+  });
+});
diff --git a/lib/src/utils.ts b/lib/src/utils.ts
index 56c02dfa..ef108bf9 100644
--- a/lib/src/utils.ts
+++ b/lib/src/utils.ts
@@ -90,8 +90,14 @@ export function valueError(message: string, name?: string): Error {
 export function pathToUrlString(path: string): string {
   if (p.isAbsolute(path)) return url.pathToFileURL(path).toString();
 
-  const components = p.sep === '\\' ? path.split(/[/\\]/) : path.split('/');
-  return components.map(encodeURIComponent).join('/');
+  // percent encode relative path like `pathToFileURL`
+  return encodeURI(path)
+    .replace(/[#?]/g, encodeURIComponent)
+    .replace(
+      process.platform === 'win32' ? /%(5B|5C|5D|5E|7C)/g : /%(5B|5D|5E|7C)/g,
+      decodeURIComponent
+    )
+    .replace(/\\/g, '/');
 }
 
 /**