diff --git a/src/pyj/read_book/prefs/head_foot.pyj b/src/pyj/read_book/prefs/head_foot.pyj
index 6eae29f6fd..212e0c5f3a 100644
--- a/src/pyj/read_book/prefs/head_foot.pyj
+++ b/src/pyj/read_book/prefs/head_foot.pyj
@@ -128,6 +128,8 @@ def format_time_left(seconds):
 
 
 def format_pos(progress_frac, length):
+    if length < 1:
+        return ''
     pages = Math.ceil(length / 1000)
     pos = progress_frac * pages
     return f'{pos:.1f} / {pages}'