diff --git a/scripts/target_config.lua b/scripts/target_config.lua
index 452d4f19..28ea4153 100755
--- a/scripts/target_config.lua
+++ b/scripts/target_config.lua
@@ -1,24 +1,5 @@
-local funcs = {}
+local lib = dofile('scripts/target_config_lib.lua')
 
-function funcs.config_message(config, _, ...)
-	config(...)
-end
-
-function funcs.config_package(config, pkg, value)
-	config('CONFIG_PACKAGE_%s=%s', pkg, value)
-end
-
-local lib = dofile('scripts/target_config_lib.lua')(funcs)
-
-
-local output = {}
-
-for config in pairs(lib.configs) do
-	table.insert(output, config)
-end
-
--- The sort will make =y entries override =m ones
-table.sort(output)
-for _, line in ipairs(output) do
-	io.stdout:write(line, '\n')
+for _, config in pairs(lib.configs) do
+	io.stdout:write(config:format(), '\n')
 end
diff --git a/scripts/target_config_check.lua b/scripts/target_config_check.lua
index 373cf430..9be50585 100755
--- a/scripts/target_config_check.lua
+++ b/scripts/target_config_check.lua
@@ -1,16 +1,12 @@
-local errors = {}
+local errors = false
 
-
-local function fail(...)
-	if not next(errors) then
+local function fail(msg)
+	if not errors then
+		errors = true
 		io.stderr:write('Configuration failed:', '\n')
 	end
 
-	local msg = string.format(...)
-	if not errors[msg] then
-		errors[msg] = true
-		io.stderr:write(' * ', msg, '\n')
-	end
+	io.stderr:write(' * ', msg, '\n')
 end
 
 local function match_config(f)
@@ -23,49 +19,21 @@ local function match_config(f)
 	return false
 end
 
-local function check_config(pattern)
-	return match_config(function(line) return line == pattern end)
-end
-
-local function check_config_prefix(pattern)
-	return match_config(function(line) return string.sub(line, 1, -2) == pattern end)
+local function check_config(config)
+	return match_config(function(line) return line == config end)
 end
 
 
-local funcs = {}
+local lib = dofile('scripts/target_config_lib.lua')
 
-function funcs.config_message(_, message, ...)
-	local pattern = string.format(...)
-
-	if not check_config(pattern) then
-		fail('%s', message)
-	end
-end
-
-function funcs.config_package(_, pkg, value)
-	local pattern = string.format('CONFIG_PACKAGE_%s=%s', pkg, value)
-	local res
-	if value == 'y' then
-		res = check_config(pattern)
-	else
-		res = check_config_prefix(string.sub(pattern, 1, -2))
-	end
-
-	if not res then
-		fail("unable to enable package '%s'", pkg)
-	end
-end
-
-local lib = dofile('scripts/target_config_lib.lua')(funcs)
-
-for config, v in pairs(lib.configs) do
-	if v == 2 then
-		if not check_config(config) then
-			fail("unable to set '%s'", config)
+for _, config in pairs(lib.configs) do
+	if config.required then
+		if not check_config(config:format()) then
+			fail(config.required)
 		end
 	end
 end
 
-if next(errors) then
+if errors then
 	os.exit(1)
 end
diff --git a/scripts/target_config_lib.lua b/scripts/target_config_lib.lua
index ee2bf006..fc897d68 100644
--- a/scripts/target_config_lib.lua
+++ b/scripts/target_config_lib.lua
@@ -1,3 +1,20 @@
+local lib = dofile('scripts/target_lib.lua')
+local env = lib.env
+
+local target = env.GLUON_TARGET
+
+assert(target)
+assert(env.BOARD)
+assert(env.SUBTARGET)
+
+local openwrt_config_target
+if env.SUBTARGET ~= '' then
+	openwrt_config_target = env.BOARD .. '_' .. env.SUBTARGET
+else
+	openwrt_config_target = env.BOARD
+end
+
+
 -- Split a string into words
 local function split(s)
 	local ret = {}
@@ -40,133 +57,138 @@ local function compact_list(list, keep_neg)
 	return ret
 end
 
-return function(funcs)
-	local lib = dofile('scripts/target_lib.lua')
-	local env = lib.env
 
-	local target = env.GLUON_TARGET
-
-	assert(target)
-	assert(env.BOARD)
-	assert(env.SUBTARGET)
-
-	local openwrt_config_target
-	if env.SUBTARGET ~= '' then
-		openwrt_config_target = env.BOARD .. '_' .. env.SUBTARGET
-	else
-		openwrt_config_target = env.BOARD
-	end
-
-
-	local function site_vars(var)
-		return lib.exec_capture_raw(string.format([[
-	MAKEFLAGS= make print _GLUON_SITE_VARS_=%s --no-print-directory -s -f - <<'END_MAKE'
+local function site_vars(var)
+	return lib.exec_capture_raw(string.format(
+[[
+MAKEFLAGS= make print _GLUON_SITE_VARS_=%s --no-print-directory -s -f - <<'END_MAKE'
 include $(GLUON_SITEDIR)/site.mk
 
 print:
 	echo -n '$(_GLUON_SITE_VARS_)'
 END_MAKE
-		]], lib.escape(var)))
+]],
+	lib.escape(var)))
+end
+
+local function site_packages(image)
+	return split(site_vars(string.format('$(GLUON_%s_SITE_PACKAGES)', image)))
+end
+
+-- TODO: Rewrite features.sh in Lua
+local function feature_packages(features)
+	-- Ugly hack: Lua doesn't give us the return code of a popened
+	-- command, so we match on a special __ERROR__ marker
+	local pkgs = lib.exec_capture({'scripts/features.sh', features}, '|| echo __ERROR__')
+	assert(string.find(pkgs, '__ERROR__') == nil, 'Error while evaluating features')
+	return pkgs
+end
+
+-- This involves running lots of processes to evaluate site.mk, so we
+-- add a simple cache
+local class_cache = {}
+local function class_packages(class)
+	if class_cache[class] then
+		return class_cache[class]
 	end
 
-	local function site_packages(image)
-		return split(site_vars(string.format('$(GLUON_%s_SITE_PACKAGES)', image)))
-	end
+	local features = site_vars(string.format('$(GLUON_FEATURES) $(GLUON_FEATURES_%s)', class))
+	features = table.concat(compact_list(split(features), false), ' ')
 
-	-- TODO: Rewrite features.sh in Lua
-	local function feature_packages(features)
-		-- Ugly hack: Lua doesn't give us the return code of a popened
-		-- command, so we match on a special __ERROR__ marker
-		local pkgs = lib.exec_capture({'scripts/features.sh', features}, '|| echo __ERROR__')
-		assert(string.find(pkgs, '__ERROR__') == nil, 'Error while evaluating features')
-		return pkgs
-	end
+	local pkgs = feature_packages(features)
+	pkgs = pkgs .. ' ' .. site_vars(string.format('$(GLUON_SITE_PACKAGES) $(GLUON_SITE_PACKAGES_%s)', class))
 
-	-- This involves running lots of processes to evaluate site.mk, so we
-	-- add a simple cache
-	local class_cache = {}
-	local function class_packages(class)
-		if class_cache[class] then
-			return class_cache[class]
+	pkgs = compact_list(split(pkgs))
+
+	class_cache[class] = pkgs
+	return pkgs
+end
+
+local enabled_packages = {}
+-- Arguments: package name and config value (true: y, nil: m, false: unset)
+-- Ensures precedence of y > m > unset
+local function config_package(pkg, v)
+	if v == false then
+		if not enabled_packages[pkg] then
+			lib.try_config('PACKAGE_' .. pkg, false)
 		end
-
-		local features = site_vars(string.format('$(GLUON_FEATURES) $(GLUON_FEATURES_%s)', class))
-		features = table.concat(compact_list(split(features), false), ' ')
-
-		local pkgs = feature_packages(features)
-		pkgs = pkgs .. ' ' .. site_vars(string.format('$(GLUON_SITE_PACKAGES) $(GLUON_SITE_PACKAGES_%s)', class))
-
-		pkgs = compact_list(split(pkgs))
-
-		class_cache[class] = pkgs
-		return pkgs
+		return
 	end
 
-	local function handle_target_pkgs(pkgs)
-		for _, pkg in ipairs(pkgs) do
-			if string.sub(pkg, 1, 1) == '-' then
-				lib.try_config('# CONFIG_PACKAGE_%s is not set', string.sub(pkg, 2))
-			else
-				funcs.config_package(lib.config, pkg, 'y')
-			end
+	if v == true or not enabled_packages[pkg] then
+		lib.config('PACKAGE_' .. pkg, v, string.format("unable to enable package '%s'", pkg))
+		enabled_packages[pkg] = true
+	end
+end
+
+local function handle_target_pkgs(pkgs)
+	for _, pkg in ipairs(pkgs) do
+		if string.sub(pkg, 1, 1) == '-' then
+			config_package(string.sub(pkg, 2), false)
+		else
+			config_package(pkg, true)
 		end
 	end
+end
 
-	lib.include('generic')
-	lib.include(target)
+lib.include('generic')
+lib.include(target)
 
-	lib.check_devices()
+lib.check_devices()
 
-	if not lib.opkg then
-		lib.config '# CONFIG_SIGNED_PACKAGES is not set'
-		lib.config 'CONFIG_CLEAN_IPKG=y'
-		lib.packages {'-opkg'}
-	end
+if not lib.opkg then
+	lib.config('SIGNED_PACKAGES', false)
+	lib.config('CLEAN_IPKG', true)
+	lib.packages {'-opkg'}
+end
 
-	if #lib.devices > 0 then
-		handle_target_pkgs(lib.target_packages)
+if #lib.devices > 0 then
+	handle_target_pkgs(lib.target_packages)
 
-		for _, dev in ipairs(lib.devices) do
-			local profile = dev.options.profile or dev.name
+	for _, dev in ipairs(lib.devices) do
+		local profile = dev.options.profile or dev.name
 
-			local device_pkgs = {}
-			local function handle_pkgs(pkgs)
-				for _, pkg in ipairs(pkgs) do
-					if string.sub(pkg, 1, 1) ~= '-' then
-						funcs.config_package(lib.config, pkg, 'm')
-					end
-					device_pkgs = append_to_list(device_pkgs, pkg)
-				end
-			end
-
-			handle_pkgs(lib.target_packages)
-			handle_pkgs(class_packages(dev.options.class))
-			handle_pkgs(dev.options.packages or {})
-			handle_pkgs(site_packages(dev.image))
-
-			funcs.config_message(lib.config, string.format("unable to enable device '%s'", profile),
-				'CONFIG_TARGET_DEVICE_%s_DEVICE_%s=y', openwrt_config_target, profile)
-			lib.config('CONFIG_TARGET_DEVICE_PACKAGES_%s_DEVICE_%s="%s"',
-				openwrt_config_target, profile,
-				table.concat(device_pkgs, ' '))
-		end
-	else
-		-- x86 fallback: no devices
-		local target_pkgs = {}
+		local device_pkgs = {}
 		local function handle_pkgs(pkgs)
 			for _, pkg in ipairs(pkgs) do
-				target_pkgs = append_to_list(target_pkgs, pkg)
+				if string.sub(pkg, 1, 1) ~= '-' then
+					config_package(pkg, nil)
+				end
+				device_pkgs = append_to_list(device_pkgs, pkg)
 			end
 		end
 
-		-- Just hardcode the class for device-less targets to 'standard'
-		-- - this is x86 only at the moment, and it will have devices
-		-- in OpenWrt 19.07 + 1 as well
 		handle_pkgs(lib.target_packages)
-		handle_pkgs(class_packages('standard'))
+		handle_pkgs(class_packages(dev.options.class))
+		handle_pkgs(dev.options.packages or {})
+		handle_pkgs(site_packages(dev.image))
 
-		handle_target_pkgs(target_pkgs)
+		local profile_config = string.format('%s_DEVICE_%s', openwrt_config_target, profile)
+		lib.config(
+			'TARGET_DEVICE_' .. profile_config, true,
+			string.format("unable to enable device '%s'", profile)
+		)
+		lib.config(
+			'TARGET_DEVICE_PACKAGES_' .. profile_config,
+			table.concat(device_pkgs, ' ')
+		)
+	end
+else
+	-- x86 fallback: no devices
+	local target_pkgs = {}
+	local function handle_pkgs(pkgs)
+		for _, pkg in ipairs(pkgs) do
+			target_pkgs = append_to_list(target_pkgs, pkg)
+		end
 	end
 
-	return lib
+	-- Just hardcode the class for device-less targets to 'standard'
+	-- - this is x86 only at the moment, and it will have devices
+	-- in OpenWrt 19.07 + 1 as well
+	handle_pkgs(lib.target_packages)
+	handle_pkgs(class_packages('standard'))
+
+	handle_target_pkgs(target_pkgs)
 end
+
+return lib
diff --git a/scripts/target_lib.lua b/scripts/target_lib.lua
index 0fc2d8b6..bb974659 100644
--- a/scripts/target_lib.lua
+++ b/scripts/target_lib.lua
@@ -150,14 +150,51 @@ local function add_image(image)
 	table.insert(M.images[device], setmetatable(image, image_mt))
 end
 
-function F.try_config(...)
-	M.configs[string.format(...)] = 1
+
+local function format_config(k, v)
+	local format
+	if type(v) == 'string' then
+		format = '%s=%q'
+	elseif v == true then
+		format = '%s=y'
+	elseif v == nil then
+		format = '%s=m'
+	elseif v == false then
+		format = '# %s is not set'
+	else
+		format = '%s=%d'
+	end
+	return string.format(format, 'CONFIG_' .. k, v)
 end
 
-function F.config(...)
-	M.configs[string.format(...)] = 2
+local config_mt = {
+	__index = {
+		format = function(config)
+			return format_config(config.key, config.value)
+		end,
+	}
+}
+
+local function do_config(k, v, required)
+	M.configs[k] = setmetatable({
+		key = k,
+		value = v,
+		required = required,
+	}, config_mt)
 end
 
+function F.try_config(k, v)
+	do_config(k, v)
+end
+
+function F.config(k, v, message)
+	if not message then
+		message = string.format("unable to set '%s'", format_config(k, v))
+	end
+	do_config(k, v, message)
+end
+
+
 function F.packages(pkgs)
 	for _, pkg in ipairs(pkgs) do
 		table.insert(M.target_packages, pkg)
@@ -165,6 +202,14 @@ function F.packages(pkgs)
 end
 M.packages = F.packages
 
+local function as_table(v)
+	if type(v) == 'table' then
+		return v
+	else
+		return {v}
+	end
+end
+
 function F.device(image, name, options)
 	options = merge(default_options, options)
 
@@ -196,16 +241,17 @@ function F.device(image, name, options)
 	end
 
 	if options.factory then
-		add_image {
-			image = image,
-			name = name,
-			subdir = 'factory',
-			in_suffix = options.factory,
-			out_suffix = '',
-			extension = options.factory_ext,
-			aliases = options.aliases,
-			manifest_aliases = options.manifest_aliases,
-		}
+		for _, ext in ipairs(as_table(options.factory_ext)) do
+			add_image {
+				image = image,
+				name = name,
+				subdir = 'factory',
+				in_suffix = options.factory,
+				out_suffix = '',
+				extension = ext,
+				aliases = options.aliases,
+			}
+		end
 	end
 	for _, extra_image in ipairs(options.extra_images) do
 		add_image {
@@ -216,7 +262,6 @@ function F.device(image, name, options)
 			out_suffix = extra_image[2],
 			extension = extra_image[3],
 			aliases = options.aliases,
-			manifest_aliases = options.manifest_aliases,
 		}
 	end
 end
@@ -240,7 +285,6 @@ function F.factory_image(image, name, ext, options)
 		out_suffix = '',
 		extension = ext,
 		aliases = options.aliases,
-		manifest_aliases = options.manifest_aliases,
 	}
 end
 
diff --git a/targets/ar71xx-generic b/targets/ar71xx-generic
index 04d798ab..a31d78b2 100644
--- a/targets/ar71xx-generic
+++ b/targets/ar71xx-generic
@@ -1,5 +1,5 @@
-config 'CONFIG_GLUON_SPECIALIZE_KERNEL=y'
-config 'CONFIG_TARGET_SQUASHFS_BLOCK_SIZE=64'
+config('GLUON_SPECIALIZE_KERNEL', true)
+config('TARGET_SQUASHFS_BLOCK_SIZE', 64)
 
 local ATH10K_PACKAGES = {
 	'kmod-ath10k',
diff --git a/targets/ar71xx-mikrotik b/targets/ar71xx-mikrotik
index 6a783b5e..81a053f2 100644
--- a/targets/ar71xx-mikrotik
+++ b/targets/ar71xx-mikrotik
@@ -1,4 +1,4 @@
-config 'CONFIG_GLUON_SPECIALIZE_KERNEL=y'
+config('GLUON_SPECIALIZE_KERNEL', true)
 
 defaults {
 	factory = false,
diff --git a/targets/ar71xx-nand b/targets/ar71xx-nand
index e52b82e0..89afd52c 100644
--- a/targets/ar71xx-nand
+++ b/targets/ar71xx-nand
@@ -1,4 +1,4 @@
-config 'CONFIG_GLUON_SPECIALIZE_KERNEL=y'
+config('GLUON_SPECIALIZE_KERNEL', true)
 
 local ATH10K_PACKAGES = {'kmod-ath10k', '-kmod-ath10k-ct', 'ath10k-firmware-qca988x', '-ath10k-firmware-qca988x-ct'}
 
diff --git a/targets/ar71xx-tiny b/targets/ar71xx-tiny
index bc9f03c8..a0a8d510 100644
--- a/targets/ar71xx-tiny
+++ b/targets/ar71xx-tiny
@@ -1,4 +1,4 @@
-config 'CONFIG_GLUON_SPECIALIZE_KERNEL=y'
+config('GLUON_SPECIALIZE_KERNEL', true)
 
 no_opkg()
 
diff --git a/targets/generic b/targets/generic
index 91ab783c..e0285821 100644
--- a/targets/generic
+++ b/targets/generic
@@ -1,21 +1,21 @@
 assert(env.GLUON_LANGS)
 
 
-config('CONFIG_GLUON_SITEDIR="%s"', env.GLUON_SITEDIR)
-config('CONFIG_GLUON_RELEASE="%s"', env.GLUON_RELEASE)
-try_config('CONFIG_GLUON_BRANCH="%s"', env.GLUON_BRANCH or '')
+config('GLUON_SITEDIR', env.GLUON_SITEDIR)
+config('GLUON_RELEASE', env.GLUON_RELEASE)
+try_config('GLUON_BRANCH', env.GLUON_BRANCH or '')
 
 for lang in string.gmatch(env.GLUON_LANGS, '%S+') do
-	try_config('CONFIG_GLUON_WEB_LANG_%s=y', lang)
+	try_config('GLUON_WEB_LANG_' .. lang, true)
 end
 
-config('CONFIG_TARGET_%s=y', env.BOARD)
+config('TARGET_' .. env.BOARD, true)
 if env.SUBTARGET ~= '' then
-	config('CONFIG_TARGET_%s_%s=y', env.BOARD, env.SUBTARGET)
+	config(string.format('TARGET_%s_%s', env.BOARD, env.SUBTARGET), true)
 end
 
 -- Disable non-default feeds in distfeeds.conf
-config('# CONFIG_FEED_gluon_base is not set')
+config('FEED_gluon_base', false)
 
 local default_feeds = {}
 for feed in string.gmatch(exec_capture_raw('. scripts/default_feeds.sh && echo "$DEFAULT_FEEDS"'), '%S+') do
@@ -24,52 +24,46 @@ end
 
 for feed in string.gmatch(exec_capture_raw('. scripts/modules.sh && echo -n "$FEEDS"'), '%S+') do
 	if not default_feeds[feed] then
-		config('# CONFIG_FEED_%s is not set', feed)
+		config('FEED_' .. feed, false)
 	end
 end
 
 
-config '# CONFIG_TARGET_ROOTFS_INITRAMFS is not set'
+config('TARGET_ROOTFS_INITRAMFS', false)
 
-config 'CONFIG_DEVEL=y'
-config 'CONFIG_ALL_NONSHARED=y'
+config('DEVEL', true)
+config('ALL_NONSHARED', true)
 
-config '# CONFIG_PACKAGE_usbip is not set' -- fails to build
-config '# CONFIG_PACKAGE_kmod-jool is not set' -- fails to build
+config('PACKAGE_usbip', false) -- fails to build
+config('PACKAGE_kmod-jool', false) -- fails to build
 
-config 'CONFIG_BUSYBOX_CUSTOM=y'
-config '# CONFIG_BUSYBOX_CONFIG_FEATURE_PREFER_IPV4_ADDRESS is not set'
+config('BUSYBOX_CUSTOM', true)
+config('BUSYBOX_CONFIG_FEATURE_PREFER_IPV4_ADDRESS', false)
 
-config 'CONFIG_PACKAGE_ATH_DEBUG=y'
+config('PACKAGE_ATH_DEBUG', true)
 
-try_config 'CONFIG_TARGET_SQUASHFS_BLOCK_SIZE=256'
+try_config('TARGET_SQUASHFS_BLOCK_SIZE', 256)
 
-config '# CONFIG_KERNEL_IP_MROUTE is not set'
-config '# CONFIG_KERNEL_IPV6_MROUTE is not set'
+config('KERNEL_IP_MROUTE', false)
+config('KERNEL_IPV6_MROUTE', false)
 
-try_config 'CONFIG_TARGET_MULTI_PROFILE=y'
-try_config 'CONFIG_TARGET_PER_DEVICE_ROOTFS=y'
+try_config('TARGET_MULTI_PROFILE', true)
+try_config('TARGET_PER_DEVICE_ROOTFS', true)
 
-if istrue(env.GLUON_MULTIDOMAIN) then
-	config 'CONFIG_GLUON_MULTIDOMAIN=y'
-end
+config('GLUON_MULTIDOMAIN', istrue(env.GLUON_MULTIDOMAIN))
 
-if istrue(env.GLUON_AUTOREMOVE) then
-	config 'CONFIG_AUTOREMOVE=y'
-end
+config('AUTOREMOVE', istrue(env.GLUON_AUTOREMOVE))
 
 if istrue(env.GLUON_DEBUG) then
-	config 'CONFIG_DEBUG=y'
-	config 'CONFIG_NO_STRIP=y'
-	config '# CONFIG_USE_STRIP is not set'
-	config '# CONFIG_USE_SSTRIP is not set'
+	config('DEBUG', true)
+	config('NO_STRIP', true)
+	config('USE_STRIP', false)
+	config('USE_SSTRIP', false)
 
-	try_config 'CONFIG_TARGET_ROOTFS_PARTSIZE=500'
+	try_config('TARGET_ROOTFS_PARTSIZE', 500)
 end
 
-if not istrue(env.GLUON_MINIFY) then
-	config '# CONFIG_GLUON_MINIFY is not set'
-end
+config('GLUON_MINIFY', istrue(env.GLUON_MINIFY))
 
 packages {
 	'-kmod-ipt-offload',
diff --git a/targets/ramips-rt305x b/targets/ramips-rt305x
index a4026e24..8678f12e 100644
--- a/targets/ramips-rt305x
+++ b/targets/ramips-rt305x
@@ -1,5 +1,5 @@
-config '# CONFIG_KERNEL_KALLSYMS is not set'
-config 'CONFIG_GLUON_SPECIALIZE_KERNEL=y'
+config('KERNEL_KALLSYMS', false)
+config('GLUON_SPECIALIZE_KERNEL', true)
 
 no_opkg()
 
diff --git a/targets/x86.inc b/targets/x86.inc
index 9536e805..c6037c68 100644
--- a/targets/x86.inc
+++ b/targets/x86.inc
@@ -1,5 +1,5 @@
-config 'CONFIG_VDI_IMAGES=y'
-config 'CONFIG_VMDK_IMAGES=y'
+config('VDI_IMAGES', true)
+config('VMDK_IMAGES', true)
 
 packages {
 	'kmod-3c59x',