diff --git a/bookish/routes/convert.py b/bookish/routes/convert.py
index 09be68c..c55f70e 100644
--- a/bookish/routes/convert.py
+++ b/bookish/routes/convert.py
@@ -88,6 +88,7 @@ def upload():
         "input_format": input_ext,
         "output_format": output_format,
         "filename": filename,
+        "stored_filename": unique_name,
     })
 
 
diff --git a/bookish/static/js/main.js b/bookish/static/js/main.js
index d5561a0..5ea0c68 100644
--- a/bookish/static/js/main.js
+++ b/bookish/static/js/main.js
@@ -87,7 +87,7 @@
             }
 
             currentTaskId = data.task_id;
-            readerFileId = data.filename;
+            readerFileId = data.stored_filename || data.filename;
 
             // Connect SSE for progress
             connectSSE(currentTaskId);
diff --git a/bookish/static/js/reader.js b/bookish/static/js/reader.js
index 57fe22b..f087895 100644
--- a/bookish/static/js/reader.js
+++ b/bookish/static/js/reader.js
@@ -550,8 +550,8 @@
             .then((r) => r.json())
             .then((data) => {
                 if (data.task_id) {
-                    const ext = file.name.split(".").pop().toLowerCase();
-                    const encoded = encodeURIComponent(data.filename);
+                    const stored = data.stored_filename || data.filename;
+                    const encoded = encodeURIComponent(stored);
                     // We'll just redirect to reader page after upload completes
                     // For simplicity, redirect immediately
                     window.location.href = `/reader/${encoded}`;