diff --git a/src/pyj/read_book/flow_mode.pyj b/src/pyj/read_book/flow_mode.pyj
index 725eb80095..c35ef1f79c 100644
--- a/src/pyj/read_book/flow_mode.pyj
+++ b/src/pyj/read_book/flow_mode.pyj
@@ -140,10 +140,10 @@ def handle_shortcut(sc_name, evt):
         goto_boundary(1)
         return True
     if sc_name is 'left':
-        window.scrollBy(-15)
+        window.scrollBy(-15, 0)
         return True
     if sc_name is 'right':
-        window.scrollBy(-15)
+        window.scrollBy(15, 0)
         return True
     if sc_name is 'start_of_book':
         get_boss().send_message('goto_doc_boundary', start=True)