diff --git a/src/plugins/helpers.js b/src/plugins/helpers.js
index ef1d2ce..4b2c6fc 100644
--- a/src/plugins/helpers.js
+++ b/src/plugins/helpers.js
@@ -4,6 +4,21 @@ import { dirname } from 'node:path';
 
 import { packageUp } from 'package-up';
 
+/**
+ * I used to use \0 for the prefix, but when explicitly
+ * using the prefix in our own virtual modules (importing other virtual modules),
+ * we get an error:
+ *   Module not found:
+ *     TypeError [ERR_INVALID_ARG_VALUE]:
+ *       The argument 'path' must be a string, Uint8Array, or URL without null bytes.
+ *       Received '<consuming-project-path>/node_modules/\x00kolay/package.json'
+ *
+ * I had also tried using `virtual:` for a prefix, but webpack doesn't allow that
+ *   Webpack supports "data:" and "file:" URIs by default
+ *   You may need an additional plugin to handle "virtual:" URIs.
+ */
+export const INTERNAL_PREFIX = `[virtual:kolay]`;
+
 const require = createRequire(import.meta.url);
 
 /**
@@ -79,21 +94,21 @@ export function virtualFile(options) {
     resolveId(id) {
       if (allowed.has(id)) {
         return {
-          id: `\0${id}`,
+          id: `${INTERNAL_PREFIX}${id}`,
         };
       }
 
       return;
     },
     loadInclude(id) {
-      if (!id.startsWith('\0')) return false;
+      if (!id.startsWith(INTERNAL_PREFIX)) return false;
 
-      return allowed.has(id.slice(1));
+      return allowed.has(id.slice(INTERNAL_PREFIX.length));
     },
     load(id) {
-      if (!id.startsWith('\0')) return;
+      if (!id.startsWith(INTERNAL_PREFIX)) return;
 
-      let importPath = id.slice(1);
+      let importPath = id.slice(INTERNAL_PREFIX.length);
 
       if (!allowed.has(importPath)) return;
 
diff --git a/src/plugins/setup.js b/src/plugins/setup.js
index 5a33ebb..4d16c84 100644
--- a/src/plugins/setup.js
+++ b/src/plugins/setup.js
@@ -4,7 +4,7 @@
 import { stripIndent } from 'common-tags';
 import { createUnplugin } from 'unplugin';
 
-import { virtualFile } from './helpers.js';
+import { INTERNAL_PREFIX, virtualFile } from './helpers.js';
 
 export const setup = createUnplugin(() => {
   return {
@@ -39,8 +39,8 @@ export const setup = createUnplugin(() => {
             //       If you find yourself reading this comment, 
             //       be sure to have both plugins setup in your plugins array.
             let [apiDocs, manifest] = await Promise.all([
-              import('kolay/api-docs:virtual'),
-              import('kolay/manifest:virtual'),
+              import('${INTERNAL_PREFIX}kolay/api-docs:virtual'),
+              import('${INTERNAL_PREFIX}kolay/manifest:virtual'),
             ]);
 
             await docs.setup({
@@ -56,7 +56,7 @@ export const setup = createUnplugin(() => {
       {
         importPath: 'kolay/test-support',
         content: stripIndent`
-          import { setupKolay as setup } from 'kolay/setup';
+          import { setupKolay as setup } from '${INTERNAL_PREFIX}kolay/setup';
 
           export function setupKolay(hooks, config) {
             hooks.beforeEach(async function () {