diff --git a/bookwyrm/views/books/series.py b/bookwyrm/views/books/series.py
index 14a2a82c5..98e3841d3 100644
--- a/bookwyrm/views/books/series.py
+++ b/bookwyrm/views/books/series.py
@@ -41,7 +41,7 @@ class BookSeriesBy(View):
                 unsortable_books.append(result)
 
         list_results = (
-            sorted(numbered_books, key=lambda book: book.series_number)
+            sorted(numbered_books, key=lambda book: int(book.series_number))
             + sorted(
                 dated_books,
                 key=lambda book: book.first_published_date