diff --git a/imagebutton.lua b/imagebutton.lua
index 0cf544a..e280744 100644
--- a/imagebutton.lua
+++ b/imagebutton.lua
@@ -1,4 +1,5 @@
 -- This file is part of SUIT, copyright (c) 2016 Matthias Richter
+local floor = math.floor;
 
 local BASE = (...):match('(.-)[^%.]+$')
 
@@ -13,7 +14,7 @@ return function(core, normal, ...)
 	opt.state = core:registerMouseHit(opt.id, x,y, function(u,v)
 		local id = opt.normal:getData()
 		assert(id:typeOf("ImageData"), "Can only use uncompressed images")
-		u, v = math.floor(u+.5), math.floor(v+.5)
+		u, v = floor(u+.5), floor(v+.5)
 		if u < 0 or u >= opt.normal:getWidth() or v < 0 or v >= opt.normal:getHeight() then
 			return false
 		end
diff --git a/input.lua b/input.lua
index 5262c2b..d60b1c1 100644
--- a/input.lua
+++ b/input.lua
@@ -1,4 +1,5 @@
 -- This file is part of SUIT, copyright (c) 2016 Matthias Richter
+local min, max, concat = math.min, math.max, table.concat;
 
 local BASE = (...):match('(.-)[^%.]+$')
 local utf8 = require 'utf8'
@@ -18,7 +19,7 @@ return function(core, input, ...)
 	h = h or opt.font:getHeight() + 4
 
 	input.text = input.text or ""
-	input.cursor = math.max(1, math.min(utf8.len(input.text)+1, input.cursor or utf8.len(input.text)+1))
+	input.cursor = max(1, min(utf8.len(input.text)+1, input.cursor or utf8.len(input.text)+1))
 	-- cursor is position *before* the character (including EOS) i.e. in "hello":
 	--   position 1: |hello
 	--   position 2: h|ello
@@ -57,26 +58,26 @@ return function(core, input, ...)
 		-- text input
 		if char and char ~= "" then
 			local a,b = split(input.text, input.cursor)
-			input.text = table.concat{a, char, b}
+			input.text = concat{a, char, b}
 			input.cursor = input.cursor + utf8.len(char)
 		end
 
 		-- text editing
 		if keycode == 'backspace' then
 			local a,b = split(input.text, input.cursor)
-			input.text = table.concat{split(a,utf8.len(a)), b}
-			input.cursor = math.max(1, input.cursor-1)
+			input.text = concat{split(a,utf8.len(a)), b}
+			input.cursor = max(1, input.cursor-1)
 		elseif keycode == 'delete' then
 			local a,b = split(input.text, input.cursor)
 			local _,b = split(b, 2)
-			input.text = table.concat{a, b}
+			input.text = concat{a, b}
 		end
 
 		-- cursor movement
 		if keycode =='left' then
-			input.cursor = math.max(0, input.cursor-1)
+			input.cursor = max(0, input.cursor-1)
 		elseif keycode =='right' then -- cursor movement
-			input.cursor = math.min(utf8.len(input.text)+1, input.cursor+1)
+			input.cursor = min(utf8.len(input.text)+1, input.cursor+1)
 		elseif keycode =='home' then -- cursor movement
 			input.cursor = 1
 		elseif keycode =='end' then -- cursor movement
diff --git a/layout.lua b/layout.lua
index 58c7034..ffd6258 100644
--- a/layout.lua
+++ b/layout.lua
@@ -1,4 +1,5 @@
 -- This file is part of SUIT, copyright (c) 2016 Matthias Richter
+local min, max, floor, ceil = math.min, math.max, math.floor, math.ceil;
 
 local Layout = {}
 function Layout.new(x,y,padx,pady)
@@ -73,7 +74,7 @@ function Layout:pop()
 	self._isFirstCell = false
 	self._stack[#self._stack] = nil
 
-	self._w, self._h = math.max(w, self._w or 0), math.max(h, self._h or 0)
+	self._w, self._h = max(w, self._w or 0), max(h, self._h or 0)
 
 	return w, h
 end
@@ -85,7 +86,7 @@ local function insert_sorted_helper(t, i0, i1, v)
 		return
 	end
 
-	local i = i0 + math.floor((i1-i0)/2)
+	local i = i0 + floor((i1-i0)/2)
 	if t[i] < v then
 		return insert_sorted_helper(t, i+1, i1, v)
 	elseif t[i] > v then
@@ -108,7 +109,7 @@ local function calc_width_height(self, w, h)
 	elseif w == "min" then
 		w = self._widths[1]
 	elseif w == "median" then
-		w = self._widths[math.ceil(#self._widths/2)] or 0
+		w = self._widths[ceil(#self._widths/2)] or 0
 	elseif type(w) ~= "number" then
 		error("width: invalid value (" .. tostring(w) .. ")", 3)
 	end
@@ -120,7 +121,7 @@ local function calc_width_height(self, w, h)
 	elseif h == "min" then
 		h = self._heights[1]
 	elseif h == "median" then
-		h = self._heights[math.ceil(#self._heights/2)] or 0
+		h = self._heights[ceil(#self._heights/2)] or 0
 	elseif type(h) ~= "number" then
 		error("width: invalid value (" .. tostring(w) .. ")", 3)
 	end
diff --git a/slider.lua b/slider.lua
index d540348..fdacc66 100644
--- a/slider.lua
+++ b/slider.lua
@@ -1,14 +1,15 @@
 -- This file is part of SUIT, copyright (c) 2016 Matthias Richter
 
 local BASE = (...):match('(.-)[^%.]+$')
+local min, max = math.min, math.max;
 
 return function(core, info, ...)
 	local opt, x,y,w,h = core.getOptionsAndSize(...)
 
 	opt.id = opt.id or info
 
-	info.min = info.min or math.min(info.value, 0)
-	info.max = info.max or math.max(info.value, 1)
+	info.min = info.min or min(info.value, 0)
+	info.max = info.max or max(info.value, 1)
 	info.step = info.step or (info.max - info.min) / 10
 	local fraction = (info.value - info.min) / (info.max - info.min)
 	local value_changed = false
@@ -19,9 +20,9 @@ return function(core, info, ...)
 		-- mouse update
 		local mx,my = core:getMousePosition()
 		if opt.vertical then
-			fraction = math.min(1, math.max(0, (y+h - my) / h))
+			fraction = min(1, max(0, (y+h - my) / h))
 		else
-			fraction = math.min(1, math.max(0, (mx - x) / w))
+			fraction = min(1, max(0, (mx - x) / w))
 		end
 		local v = fraction * (info.max - info.min) + info.min
 		if v ~= info.value then
@@ -33,10 +34,10 @@ return function(core, info, ...)
 		local key_up = opt.vertical and 'up' or 'right'
 		local key_down = opt.vertical and 'down' or 'left'
 		if core:getPressedKey() == key_up then
-			info.value = math.min(info.max, info.value + info.step)
+			info.value = min(info.max, info.value + info.step)
 			value_changed = true
 		elseif core:getPressedKey() == key_down then
-			info.value = math.max(info.min, info.value - info.step)
+			info.value = max(info.min, info.value - info.step)
 			value_changed = true
 		end
 	end
diff --git a/theme.lua b/theme.lua
index 5f6d3b6..446fb42 100644
--- a/theme.lua
+++ b/theme.lua
@@ -1,6 +1,7 @@
 -- This file is part of SUIT, copyright (c) 2016 Matthias Richter
 
 local BASE = (...):match('(.-)[^%.]+$')
+local min, max = math.min, math.max;
 
 local theme = {}
 theme.cornerRadius = 4
@@ -21,7 +22,7 @@ end
 function theme.drawBox(x,y,w,h, colors, cornerRadius)
 	colors = colors or theme.getColorForState(opt)
 	cornerRadius = cornerRadius or theme.cornerRadius
-	w = math.max(cornerRadius/2, w)
+	w = max(cornerRadius/2, w)
 	if h < cornerRadius/2 then
 		y,h = y - (cornerRadius - h), cornerRadius/2
 	end
@@ -82,7 +83,7 @@ end
 
 function theme.Slider(fraction, opt, x,y,w,h)
 	local xb, yb, wb, hb -- size of the progress bar
-	local r =  math.min(w,h) / 2.1
+	local r =  min(w,h) / 2.1
 	if opt.vertical then
 		x, w = x + w*.25, w*.5
 		xb, yb, wb, hb = x, y+h*(1-fraction), w, h*fraction
@@ -107,7 +108,7 @@ end
 
 function theme.ProgressBar(fraction, opt, x,y,w,h)
 	local xb, yb, wb, hb -- size of the progress bar
-	local r =  math.min(w,h) / 2.1
+	local r =  min(w,h) / 2.1
 	if opt.vertical then
 		x, w = x + w*.25, w*.5
 		xb, yb, wb, hb = x, y+h*(1-fraction), w, h*fraction