diff --git a/kitty/rc/scroll_window.py b/kitty/rc/scroll_window.py
index 5cc86befa..bdf422dd8 100644
--- a/kitty/rc/scroll_window.py
+++ b/kitty/rc/scroll_window.py
@@ -79,6 +79,8 @@ using this option means that you will not be notified of failures.
                             if not isinstance(amt, int) and not amt.is_integer():
                                 amt = round(window.screen.lines * amt)
                                 unit = 'line'
+                            else:
+                                unit = 'page'
                             assert isinstance(amt, int)
                             direction = 'up' if amt < 0 else 'down'
                             func = getattr(window, f'scroll_{unit}_{direction}')