diff --git a/frontend/ui/reader/readerfont.lua b/frontend/ui/reader/readerfont.lua
index 8078eb558..f85f65c33 100644
--- a/frontend/ui/reader/readerfont.lua
+++ b/frontend/ui/reader/readerfont.lua
@@ -7,6 +7,7 @@ local Screen = require("ui/screen")
 local Input = require("ui/input")
 local Event = require("ui/event")
 local UIManager = require("ui/uimanager")
+local Screen = require("ui/screen")
 local _ = require("gettext")
 
 local ReaderFont = InputContainer:new{
@@ -159,7 +160,7 @@ function ReaderFont:onSetFontSize(new_size)
 		text = _("Set font size to ")..self.font_size,
 		timeout = 1,
 	})
-	self.ui.document:setFontSize(scaleByDPI(new_size))
+	self.ui.document:setFontSize(Screen:scaleByDPI(new_size))
 	self.ui:handleEvent(Event:new("UpdatePos"))
 
 	return true
diff --git a/frontend/ui/widget/buttontable.lua b/frontend/ui/widget/buttontable.lua
index 3cec732c8..328513a54 100644
--- a/frontend/ui/widget/buttontable.lua
+++ b/frontend/ui/widget/buttontable.lua
@@ -16,7 +16,7 @@ local ButtonTable = VerticalGroup:new{
 	},
 	sep_width = Screen:scaleByDPI(1),
 	padding = Screen:scaleByDPI(2),
-	
+
 	zero_sep = false,
 	button_font_face = "cfont",
 	button_font_size = 20,