diff --git a/code/game/objects/items/devices/flashlight.dm b/code/game/objects/items/devices/flashlight.dm
index 79f65907c5b..5a1f529d9d4 100644
--- a/code/game/objects/items/devices/flashlight.dm
+++ b/code/game/objects/items/devices/flashlight.dm
@@ -9,7 +9,7 @@
 	slot_flags = SLOT_BELT
 	materials = list(MAT_METAL=50, MAT_GLASS=20)
 	actions_types = list(/datum/action/item_action/toggle_light)
-	var/on = 0
+	var/on = FALSE
 	var/brightness_on = 4 //luminosity when on
 
 /obj/item/flashlight/Initialize()
@@ -85,7 +85,7 @@
 
 /obj/item/flashlight/extinguish_light()
 	if(on)
-		on = 0
+		on = FALSE
 		update_brightness()
 
 /obj/item/flashlight/pen
@@ -126,7 +126,7 @@
 	w_class = WEIGHT_CLASS_BULKY
 	flags = CONDUCT
 	materials = list()
-	on = 1
+	on = TRUE
 
 
 // green-shaded desk lamp
@@ -239,7 +239,7 @@ obj/item/flashlight/lamp/bananalamp
 	brightness_on = 6
 	light_color = "#FFBF00"
 	materials = list()
-	on = 1 //Bio-luminesence has one setting, on.
+	on = TRUE //Bio-luminesence has one setting, on.
 
 /obj/item/flashlight/slime/New()
 	set_light(brightness_on)
diff --git a/code/modules/clothing/head/hardhat.dm b/code/modules/clothing/head/hardhat.dm
index 95137650612..9392b91f75e 100644
--- a/code/modules/clothing/head/hardhat.dm
+++ b/code/modules/clothing/head/hardhat.dm
@@ -5,7 +5,7 @@
 	icon_state = "hardhat0_yellow"
 	item_state = "hardhat0_yellow"
 	var/brightness_on = 4 //luminosity when on
-	var/on = 0
+	var/on = FALSE
 	item_color = "yellow" //Determines used sprites: hardhat[on]_[color] and hardhat[on]_[color]2 (lying down sprite)
 	armor = list(melee = 15, bullet = 5, laser = 20, energy = 10, bomb = 20, bio = 10, rad = 20)
 	flags_inv = 0
@@ -28,7 +28,7 @@
 
 /obj/item/clothing/head/hardhat/extinguish_light()
 	if(on)
-		on = 0
+		on = FALSE
 		set_light(0)
 		icon_state = "hardhat0_[item_color]"
 		item_state = "hardhat0_[item_color]"
diff --git a/code/modules/mob/living/carbon/human/human.dm b/code/modules/mob/living/carbon/human/human.dm
index a4d2dfba09a..5897116f93e 100644
--- a/code/modules/mob/living/carbon/human/human.dm
+++ b/code/modules/mob/living/carbon/human/human.dm
@@ -2022,5 +2022,5 @@ Eyes need to have significantly high darksight to shine unless the mob has the X
 
 	var/obj/item/organ/internal/lantern/O = get_int_organ(/obj/item/organ/internal/lantern)
 	if(O && O.glowing)
-		O.toggle_biolum(1)
+		O.toggle_biolum(TRUE)
 		visible_message("<span class='danger'>[src] is engulfed in shadows and fades into the darkness.</span>", "<span class='danger'>A sense of dread washes over you as you suddenly dim dark.</span>")
diff --git a/code/modules/mob/living/silicon/pai/pai.dm b/code/modules/mob/living/silicon/pai/pai.dm
index 6c168838fe0..d61de439ca2 100644
--- a/code/modules/mob/living/silicon/pai/pai.dm
+++ b/code/modules/mob/living/silicon/pai/pai.dm
@@ -79,7 +79,7 @@
 	var/obj/item/integrated_radio/signal/sradio // AI's signaller
 
 	var/translator_on = 0 // keeps track of the translator module
-	var/flashlight_on = 0 //keeps track of the flashlight module
+	var/flashlight_on = FALSE //keeps track of the flashlight module
 
 	var/current_pda_messaging = null
 	var/custom_sprite = 0
@@ -620,5 +620,5 @@
 	loc = card
 
 /mob/living/silicon/pai/extinguish_light()
-	flashlight_on = 0
+	flashlight_on = FALSE
 	set_light(0)
diff --git a/code/modules/power/lighting.dm b/code/modules/power/lighting.dm
index c911a5ceb8e..99a36fdfcb4 100644
--- a/code/modules/power/lighting.dm
+++ b/code/modules/power/lighting.dm
@@ -137,7 +137,7 @@
 	idle_power_usage = 2
 	active_power_usage = 20
 	power_channel = LIGHT //Lights are calc'd via area so they dont need to be in the machine list
-	var/on = 0					// 1 if on, 0 if off
+	var/on = FALSE					// 1 if on, 0 if off
 	var/on_gs = 0
 	var/static_power_used = 0
 	var/brightness_range = 8	// luminosity when on, also used in power calculation
@@ -212,7 +212,7 @@
 /obj/machinery/light/Destroy()
 	var/area/A = get_area(src)
 	if(A)
-		on = 0
+		on = FALSE
 //		A.update_lights()
 	return ..()
 
@@ -223,13 +223,13 @@
 			icon_state = "[base_state][on]"
 		if(LIGHT_EMPTY)
 			icon_state = "[base_state]-empty"
-			on = 0
+			on = FALSE
 		if(LIGHT_BURNED)
 			icon_state = "[base_state]-burned"
-			on = 0
+			on = FALSE
 		if(LIGHT_BROKEN)
 			icon_state = "[base_state]-broken"
-			on = 0
+			on = FALSE
 	return
 
 // update the icon_state and luminosity of the light depending on its state
@@ -254,7 +254,7 @@
 				if(status == LIGHT_OK && trigger)
 					status = LIGHT_BURNED
 					icon_state = "[base_state]-burned"
-					on = 0
+					on = FALSE
 					set_light(0)
 			else
 				use_power = 2
@@ -734,6 +734,6 @@
 	return FIRELOSS
 
 /obj/machinery/light/extinguish_light()
-	on = 0
+	on = FALSE
 	visible_message("<span class='danger'>[src] flickers and falls dark.</span>")
 	update(0)