diff --git a/src/pyj/read_book/flow_mode.pyj b/src/pyj/read_book/flow_mode.pyj
index 586cca3979..725eb80095 100644
--- a/src/pyj/read_book/flow_mode.pyj
+++ b/src/pyj/read_book/flow_mode.pyj
@@ -57,7 +57,7 @@ def _check_for_scroll_end(func, obj, args, report):
     before = window.pageYOffset
     func.apply(obj, args)
     if window.pageYOffset is before:
-        get_boss().send_message('next_spine_item', previous=arguments[0] < 0)
+        get_boss().send_message('next_spine_item', previous=args[0] < 0)
         return False
     if report:
         report_human_scroll(window.pageYOffset - before)
@@ -121,9 +121,9 @@ def goto_boundary(y):
 
 
 @check_for_scroll_end_and_report
-def scroll_by_page(backward):
+def scroll_by_page(direction):
     h = scroll_viewport.height() - 10
-    window.scrollBy(0, -h if backward else h)
+    window.scrollBy(0, h * direction)
 
 
 def handle_shortcut(sc_name, evt):
@@ -152,10 +152,10 @@ def handle_shortcut(sc_name, evt):
         get_boss().send_message('goto_doc_boundary', start=False)
         return True
     if sc_name is 'pageup':
-        scroll_by_page(True)
+        scroll_by_page(-1)
         return True
     if sc_name is 'pagedown':
-        scroll_by_page(False)
+        scroll_by_page(1)
         return True
     return False
 
@@ -224,9 +224,9 @@ def handle_gesture(gesture):
         if not gesture.active and not gesture.is_held:
             flick_animator.start(gesture)
     elif gesture.type is 'prev-page':
-        scroll_by_page(True)
+        scroll_by_page(-1)
     elif gesture.type is 'next-page':
-        scroll_by_page(False)
+        scroll_by_page(1)
     elif gesture.type is 'long-tap':
         r = word_at_point(gesture.viewport_x, gesture.viewport_y)
         if r: