diff --git a/packages/histoire/src/client/app/util/sandbox.ts b/packages/histoire/src/client/app/util/sandbox.ts
index 52fd2401..20455108 100644
--- a/packages/histoire/src/client/app/util/sandbox.ts
+++ b/packages/histoire/src/client/app/util/sandbox.ts
@@ -6,5 +6,5 @@ export function getSandboxUrl (story: Story, variant: Variant) {
   const url = new URLSearchParams()
   url.append('storyId', story.id)
   url.append('variantId', variant.id)
-  return `${base}__sandbox?${url.toString()}`
+  return `${base}__sandbox.html?${url.toString()}`
 }
diff --git a/packages/histoire/src/node/build.ts b/packages/histoire/src/node/build.ts
index 29b3571a..a879b654 100644
--- a/packages/histoire/src/node/build.ts
+++ b/packages/histoire/src/node/build.ts
@@ -155,7 +155,7 @@ export async function build (ctx: Context) {
         const query = new URLSearchParams()
         query.append('storyId', story.id)
         query.append('variantId', variant.id)
-        const url = `${baseUrl}__sandbox?${query.toString()}`
+        const url = `${baseUrl}__sandbox.html?${query.toString()}`
         for (const fn of previewStoryCallbacks) {
           await fn({
             file: storyFile.path,