diff --git a/code/lib/builder-manager/src/utils/managerEntries.ts b/code/lib/builder-manager/src/utils/managerEntries.ts
index f6e85efaec5d..8794897ef7e4 100644
--- a/code/lib/builder-manager/src/utils/managerEntries.ts
+++ b/code/lib/builder-manager/src/utils/managerEntries.ts
@@ -1,5 +1,6 @@
-import { join, parse, relative } from 'path';
 import fs from 'fs-extra';
+import { join, parse, relative } from 'node:path';
+import slash from 'slash';
 import findCacheDirectory from 'find-cache-dir';
 /**
  * Manager entries should be **self-invoking** bits of code.
@@ -29,7 +30,7 @@ export async function wrapManagerEntries(entrypoints: string[]) {
 
       const location = join(cacheLocation, relative(process.cwd(), dir), `${name}-bundle.mjs`);
       await fs.ensureFile(location);
-      await fs.writeFile(location, `import '${entry}';`);
+      await fs.writeFile(location, `import '${slash(entry)}';`);
 
       return location;
     })
diff --git a/code/lib/builder-webpack5/src/preview/iframe-webpack.config.ts b/code/lib/builder-webpack5/src/preview/iframe-webpack.config.ts
index 02be5f0053fd..cb85f840dc5e 100644
--- a/code/lib/builder-webpack5/src/preview/iframe-webpack.config.ts
+++ b/code/lib/builder-webpack5/src/preview/iframe-webpack.config.ts
@@ -7,6 +7,7 @@ import CaseSensitivePathsPlugin from 'case-sensitive-paths-webpack-plugin';
 import TerserWebpackPlugin from 'terser-webpack-plugin';
 import VirtualModulePlugin from 'webpack-virtual-modules';
 import ForkTsCheckerWebpackPlugin from 'fork-ts-checker-webpack-plugin';
+import slash from 'slash';
 
 import type { Options, CoreConfig, DocsOptions, PreviewAnnotation } from '@storybook/types';
 import { globals } from '@storybook/preview/globals';
@@ -108,7 +109,7 @@ export default async (
         if (typeof entry === 'object') {
           return entry.absolute;
         }
-        return entry;
+        return slash(entry);
       }
     ),
     loadPreviewOrConfigFile(options),
diff --git a/code/lib/core-server/src/utils/get-builders.ts b/code/lib/core-server/src/utils/get-builders.ts
index 11ee9514a2d6..9f71b5e085a5 100644
--- a/code/lib/core-server/src/utils/get-builders.ts
+++ b/code/lib/core-server/src/utils/get-builders.ts
@@ -1,4 +1,5 @@
-import type { Options, CoreConfig, Builder } from '@storybook/types';
+import type { Builder, CoreConfig, Options } from '@storybook/types';
+import { pathToFileURL } from 'node:url';
 
 export async function getManagerBuilder(): Promise<Builder<unknown>> {
   return import('@storybook/builder-manager');
@@ -17,7 +18,7 @@ export async function getPreviewBuilder(
   } else {
     throw new Error('no builder configured!');
   }
-  const previewBuilder = await import(builderPackage);
+  const previewBuilder = await import(pathToFileURL(builderPackage).href);
   return previewBuilder;
 }