diff --git a/tuned/plugins/plugin_audio.py b/tuned/plugins/plugin_audio.py
index 24bca7c..18774b9 100644
--- a/tuned/plugins/plugin_audio.py
+++ b/tuned/plugins/plugin_audio.py
@@ -32,8 +32,8 @@ class VideoPlugin(tuned.plugins.Plugin):
 	@classmethod
 	def _get_default_options(cls):
 		return {
-			"enable_ac97_powersave" : "",
-			"hda_intel_powersave" : "",
+			"enable_ac97_powersave" : None,
+			"hda_intel_powersave" : None,
 			"dynamic_tuning" : "0",
 		}
 
@@ -51,11 +51,11 @@ class VideoPlugin(tuned.plugins.Plugin):
 			value = "N"
 		else:
 			log.warn("Incorrect enable_ac97_powersave value.")
-			return ""
+			return
 
 		sys_file = "/sys/module/snd_ac97_codec/parameters/power_save"
 		if not os.path.exists(sys_file):
-			return ""
+			return
 
 		old_value = tuned.utils.commands.read_file(sys_file)
 		tuned.utils.commands.write_to_file(sys_file, value)
@@ -73,7 +73,7 @@ class VideoPlugin(tuned.plugins.Plugin):
 	def _set_hda_intel_powersave(self, value):
 		sys_file = "/sys/module/snd_hda_intel/parameters/power_save"
 		if not os.path.exists(sys_file):
-			return ""
+			return
 
 		old_value = tuned.utils.commands.read_file(sys_file)
 		tuned.utils.commands.write_to_file(sys_file, value)
diff --git a/tuned/plugins/plugin_cpu.py b/tuned/plugins/plugin_cpu.py
index e47ed02..dd75053 100644
--- a/tuned/plugins/plugin_cpu.py
+++ b/tuned/plugins/plugin_cpu.py
@@ -47,10 +47,10 @@ class CPULatencyPlugin(tuned.plugins.Plugin):
 			"load_threshold" : 0.2,
 			"latency_low"    : 100,
 			"latency_high"   : 1000,
-			"latency"        : "",
-			"cpu_governor"   : "",
-			"cpu_multicore_powersave" : "",
-			"enable_usb_autosupend" : "",
+			"latency"        : None,
+			"cpu_governor"   : None,
+			"cpu_multicore_powersave" : None,
+			"enable_usb_autosupend" : None,
 		}
 
 	def cleanup(self):
@@ -107,7 +107,7 @@ class CPULatencyPlugin(tuned.plugins.Plugin):
 		old_value = tuned.utils.commands.execute(["cpupower", "info", "-m"])
 		if old_value.find("not supported") != -1:
 			log.info("cpu_multicore_powersave is not supported by this system")
-			return ""
+			return
 
 		if old_value.startswith("System's multi core scheduler setting"):
 			try:
@@ -132,7 +132,7 @@ class CPULatencyPlugin(tuned.plugins.Plugin):
 			value = "0"
 		else:
 			log.warn("Incorrect enable_bluetooth value.")
-			return ""
+			return
 		for sys_file in glob.glob("/sys/bus/usb/devices/*/power/autosuspend"):
 			old_value[sys_file] = tuned.utils.commands.read_file(sys_file)
 			tuned.utils.commands.write_to_file(sys_file, value)
diff --git a/tuned/plugins/plugin_disk.py b/tuned/plugins/plugin_disk.py
index 6e27439..ed08cfb 100644
--- a/tuned/plugins/plugin_disk.py
+++ b/tuned/plugins/plugin_disk.py
@@ -73,12 +73,12 @@ class DiskPlugin(tuned.plugins.Plugin):
 	@classmethod
 	def _get_default_options(cls):
 		return {
-			"elevator"   : "",
-			"disk_alpm"  : "",
-			"disk_apm"  : "",
-			"disk_spindown"  : "",
-			"disk_readahead_multiplier" : "",
-			"disk_scheduler_quantum" : "",
+			"elevator"   : None,
+			"disk_alpm"  : None,
+			"disk_apm"  : None,
+			"disk_spindown"  : None,
+			"disk_readahead_multiplier" : None,
+			"disk_scheduler_quantum" : None,
 		}
 
 	def _update_idle(self, dev):
@@ -204,7 +204,7 @@ class DiskPlugin(tuned.plugins.Plugin):
 	def _set_disk_apm(self, dev, value):
 		#TODO: get current value using hdparm -B. My disk does not support it...
 		tuned.utils.commands.execute(["hdparm", "-B", value, "/dev/" + dev])
-		return ""
+		return
 
 	@command_revert("disk", "disk_apm")
 	def _revert_disk_apm(self, dev, value):
@@ -221,7 +221,7 @@ class DiskPlugin(tuned.plugins.Plugin):
 
 		old_value = tuned.utils.commands.read_file(sys_file).strip()
 		if len(old_value) == 0:
-			return ""
+			return
 		new_value = int(int(old_value) * float(value))
 		
 		tuned.utils.commands.write_to_file(sys_file, new_value)
@@ -239,7 +239,7 @@ class DiskPlugin(tuned.plugins.Plugin):
 		old_value = tuned.utils.commands.read_file(sys_file).strip()
 		if len(old_value) == 0:
 			log.info("disk_scheduler_quantum option is not supported by this HW")
-			return ""
+			return
 
 		tuned.utils.commands.write_to_file(sys_file, value)
 		return old_value
diff --git a/tuned/plugins/plugin_script.py b/tuned/plugins/plugin_script.py
index ec55b9a..81eabc8 100644
--- a/tuned/plugins/plugin_script.py
+++ b/tuned/plugins/plugin_script.py
@@ -26,7 +26,7 @@ class ScriptPlugin(tuned.plugins.Plugin):
 	@classmethod
 	def _get_default_options(cls):
 		return {
-			"script"   : "",
+			"script"   : None,
 			"dynamic_tuning" : "0",
 		}
 
diff --git a/tuned/plugins/plugin_video.py b/tuned/plugins/plugin_video.py
index 6d8aa15..edb9e99 100644
--- a/tuned/plugins/plugin_video.py
+++ b/tuned/plugins/plugin_video.py
@@ -30,7 +30,7 @@ class VideoPlugin(tuned.plugins.Plugin):
 	def _get_default_options(cls):
 		return {
 			"dynamic_tuning" : "0",
-			"radeon_powersave" : "",
+			"radeon_powersave" : None,
 		}
 
 	def cleanup(self):
@@ -42,7 +42,7 @@ class VideoPlugin(tuned.plugins.Plugin):
 	@command(STORAGE_CATEGORY, "radeon_powersave")
 	def _set_radeon_powersave(self, value):
 		if not os.path.exists("/sys/class/drm/card0/device/power_method"):
-			return ""
+			return
 
 		old_values = []
 		if value in ["default", "auto", "low", "med", "high"]:
diff --git a/tuned/plugins/plugin_wireless.py b/tuned/plugins/plugin_wireless.py
index 15715e8..572f1f7 100644
--- a/tuned/plugins/plugin_wireless.py
+++ b/tuned/plugins/plugin_wireless.py
@@ -27,8 +27,8 @@ class WirelessPlugin(tuned.plugins.Plugin):
 	def _get_default_options(cls):
 		return {
 			"dynamic_tuning" : "0",
-			"wifi_power_level" : "",
-			"enable_bluetooth" : "",
+			"wifi_power_level" : None,
+			"enable_bluetooth" : None,
 		}
 
 	def cleanup(self):
@@ -43,7 +43,7 @@ class WirelessPlugin(tuned.plugins.Plugin):
 			lines = open("/proc/net/wireless").readlines()
 		except (OSError,IOError) as e:
 			log.error("Error reading wifi devices from /proc/net/wireless: %s" % (e))
-			return ""
+			return
 
 		ifaces = []
 		for line in lines:
@@ -56,7 +56,7 @@ class WirelessPlugin(tuned.plugins.Plugin):
 
 		if len(ifaces) == 0:
 			log.info("No wifi interfaces found")
-			return ""
+			return
 
 		# TODO: set old_value properly. Is there "get_power"? I don't have wifi here
 		old_value = "5"
@@ -80,7 +80,7 @@ class WirelessPlugin(tuned.plugins.Plugin):
 			tuned.utils.commands.execute(["rmmod", "hci_usb"])
 		else:
 			log.warn("Incorrect enable_bluetooth value.")
-			return ""
+			return
 
 		return old_value
 
diff --git a/tuned/utils/commands.py b/tuned/utils/commands.py
index 730c4a2..c7ef3c0 100644
--- a/tuned/utils/commands.py
+++ b/tuned/utils/commands.py
@@ -88,7 +88,7 @@ def command(plugin, key):
 				return False
 
 			old_value = target(self, *args, **kwargs)
-			if len(old_value) != 0:
+			if old_value and len(old_value) != 0:
 				storage.data[plugin][key + dev] = old_value
 				storage.save()
 			return True