diff --git a/frontend/src/components/file-renderers/index.tsx b/frontend/src/components/file-renderers/index.tsx
index b701fccf..cf6e17fd 100644
--- a/frontend/src/components/file-renderers/index.tsx
+++ b/frontend/src/components/file-renderers/index.tsx
@@ -120,7 +120,7 @@ export function FileRenderer({
   
   // Construct HTML file preview URL if we have a sandbox and the file is HTML
   const htmlPreviewUrl = (isHtmlFile && project?.sandbox?.sandbox_url && fileName) 
-    ? `${project.sandbox.sandbox_url}/${fileName.replace(/^\/workspace\//, '')}`
+    ? `${project.sandbox.sandbox_url}/${encodeURIComponent(fileName.replace(/^\/workspace\//, ''))}`
     : blobHtmlUrl; // Use blob URL as fallback
   
   // Clean up blob URL on unmount