diff --git a/code/game/dna/dna_modifier.dm b/code/game/dna/dna_modifier.dm
index c206cc7aab8..708d8467fb0 100644
--- a/code/game/dna/dna_modifier.dm
+++ b/code/game/dna/dna_modifier.dm
@@ -52,7 +52,7 @@
 /obj/machinery/dna_scannernew
 	name = "\improper DNA modifier"
 	desc = "It scans DNA structures."
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "scanner_open"
 	density = 1
 	anchored = 1.0
diff --git a/code/game/gamemodes/nuclear/nuclear.dm b/code/game/gamemodes/nuclear/nuclear.dm
index 689be7f0bfb..a3d4a89033a 100644
--- a/code/game/gamemodes/nuclear/nuclear.dm
+++ b/code/game/gamemodes/nuclear/nuclear.dm
@@ -416,7 +416,7 @@ proc/issyndicate(mob/living/M as mob)
 		text += "(Syndicates used [TC_uses] TC) [purchases]"
 
 		if(TC_uses==0 && station_was_nuked && !is_operatives_are_dead())
-			text += "<BIG><IMG CLASS=icon SRC=\ref['icons/BadAss.dmi'] ICONSTATE='badass'></BIG>"
+			text += "<BIG><IMG CLASS=icon SRC=\ref['icons/badass.dmi'] ICONSTATE='badass'></BIG>"
 
 		to_chat(world, text)
 	return 1
diff --git a/code/game/machinery/Freezer.dm b/code/game/machinery/Freezer.dm
index 5fb11e932c2..727d70392bd 100644
--- a/code/game/machinery/Freezer.dm
+++ b/code/game/machinery/Freezer.dm
@@ -1,6 +1,6 @@
 /obj/machinery/atmospherics/unary/cold_sink/freezer
 	name = "freezer"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "freezer"
 	density = 1
 	var/min_temperature = 0
@@ -161,7 +161,7 @@
 
 /obj/machinery/atmospherics/unary/heat_reservoir/heater/
 	name = "heater"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "heater"
 	density = 1
 	var/max_temperature = 0
diff --git a/code/game/machinery/Sleeper.dm b/code/game/machinery/Sleeper.dm
index c2cc979f1dc..feb70cdbae2 100644
--- a/code/game/machinery/Sleeper.dm
+++ b/code/game/machinery/Sleeper.dm
@@ -6,7 +6,7 @@
 
 /obj/machinery/sleeper
 	name = "Sleeper"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper-open"
 	var/base_icon = "sleeper"
 	density = 1
diff --git a/code/game/machinery/adv_med.dm b/code/game/machinery/adv_med.dm
index e721167b0f5..679af70526e 100644
--- a/code/game/machinery/adv_med.dm
+++ b/code/game/machinery/adv_med.dm
@@ -1,6 +1,6 @@
 /obj/machinery/bodyscanner
 	name = "body scanner"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "bodyscanner-open"
 	density = TRUE
 	dir = WEST
@@ -218,7 +218,7 @@
 
 /obj/machinery/body_scanconsole
 	name = "Body Scanner Console"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "bodyscannerconsole"
 	density = 1
 	anchored = 1
diff --git a/code/game/machinery/cryopod.dm b/code/game/machinery/cryopod.dm
index b6a02aacfd0..a1bdff99d56 100644
--- a/code/game/machinery/cryopod.dm
+++ b/code/game/machinery/cryopod.dm
@@ -12,7 +12,7 @@
 /obj/machinery/computer/cryopod
 	name = "cryogenic oversight console"
 	desc = "An interface between crew and the cryogenic storage oversight systems."
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "cellconsole"
 	circuit = /obj/item/circuitboard/cryopodcontrol
 	density = 0
@@ -167,7 +167,7 @@
 /obj/structure/cryofeed
 	name = "cryogenic feed"
 	desc = "A bewildering tangle of machinery and pipes."
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "cryo_rear"
 	anchored = 1
 
@@ -189,7 +189,7 @@
 /obj/machinery/cryopod
 	name = "cryogenic freezer"
 	desc = "A man-sized pod for entering suspended animation."
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "body_scanner_0"
 	density = 1
 	anchored = 1
diff --git a/code/game/machinery/doors/firedoor.dm b/code/game/machinery/doors/firedoor.dm
index cb1b26f4f80..773c54d2808 100644
--- a/code/game/machinery/doors/firedoor.dm
+++ b/code/game/machinery/doors/firedoor.dm
@@ -10,7 +10,7 @@
 /obj/machinery/door/firedoor
 	name = "firelock"
 	desc = "Apply crowbar."
-	icon = 'icons/obj/doors/Doorfireglass.dmi'
+	icon = 'icons/obj/doors/doorfireglass.dmi'
 	icon_state = "door_open"
 	opacity = 0
 	density = FALSE
@@ -159,7 +159,7 @@
 /obj/machinery/door/firedoor/update_icon()
 	overlays.Cut()
 	if(active_alarm && hasPower())
-		overlays += image('icons/obj/doors/Doorfire.dmi', "alarmlights")
+		overlays += image('icons/obj/doors/doorfire.dmi', "alarmlights")
 	if(density)
 		icon_state = "door_closed"
 		if(welded)
@@ -225,7 +225,7 @@
 	qdel(src)
 
 /obj/machinery/door/firedoor/border_only
-	icon = 'icons/obj/doors/edge_Doorfire.dmi'
+	icon = 'icons/obj/doors/edge_doorfire.dmi'
 	flags = ON_BORDER
 	can_crush = FALSE
 
@@ -258,7 +258,7 @@
 
 /obj/machinery/door/firedoor/heavy
 	name = "heavy firelock"
-	icon = 'icons/obj/doors/Doorfire.dmi'
+	icon = 'icons/obj/doors/doorfire.dmi'
 	glass = FALSE
 	opacity = 1
 	explosion_block = 2
@@ -280,7 +280,7 @@
 /obj/structure/firelock_frame
 	name = "firelock frame"
 	desc = "A partially completed firelock."
-	icon = 'icons/obj/doors/Doorfire.dmi'
+	icon = 'icons/obj/doors/doorfire.dmi'
 	icon_state = "frame1"
 	anchored = FALSE
 	density = TRUE
diff --git a/code/game/mecha/equipment/tools/medical_tools.dm b/code/game/mecha/equipment/tools/medical_tools.dm
index 9dc6c8e6f11..f1ad010ea93 100644
--- a/code/game/mecha/equipment/tools/medical_tools.dm
+++ b/code/game/mecha/equipment/tools/medical_tools.dm
@@ -31,7 +31,7 @@
 /obj/item/mecha_parts/mecha_equipment/medical/sleeper
 	name = "mounted sleeper"
 	desc = "Equipment for medical exosuits. A mounted sleeper that stabilizes patients and can inject reagents in the exosuit's reserves."
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	origin_tech = "engineering=3;biotech=3;plasmatech=2"
 	energy_drain = 20
diff --git a/code/modules/awaymissions/corpse.dm b/code/modules/awaymissions/corpse.dm
index 219fc5ecdbb..5414b56351a 100644
--- a/code/modules/awaymissions/corpse.dm
+++ b/code/modules/awaymissions/corpse.dm
@@ -242,7 +242,7 @@
 
 
 /obj/effect/mob_spawn/human/alive
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	death = FALSE
 	roundstart = FALSE //you could use these for alive fake humans on roundstart but this is more common scenario
@@ -256,7 +256,7 @@
 	mob_type = 	/mob/living/simple_animal/mouse
 	death = FALSE
 	roundstart = FALSE
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	flavour_text = "Squeak!"
 
@@ -267,7 +267,7 @@
 	death = FALSE
 	roundstart = FALSE
 	mob_gender = FEMALE
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	flavour_text = "Moo!"
 
@@ -306,7 +306,7 @@
 	roundstart = FALSE
 	random = TRUE
 	name = "sleeper"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	flavour_text = "<span class='big bold'>You are a space doctor!</span>"
 	assignedrole = "Space Doctor"
@@ -437,7 +437,7 @@
 	roundstart = FALSE
 	random = TRUE
 	name = "bartender sleeper"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	flavour_text = "<span class='big bold'>You are a space bartender!</span><b> Time to mix drinks and change lives.</b>"
 	assignedrole = "Space Bartender"
@@ -461,7 +461,7 @@
 	random = TRUE
 	mob_name = "Beach Bum"
 	name = "beach bum sleeper"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	flavour_text = "You are a beach bum!"
 	assignedrole = "Beach Bum"
diff --git a/code/modules/awaymissions/mission_code/ruins/oldstation.dm b/code/modules/awaymissions/mission_code/ruins/oldstation.dm
index d1f30fd6c4e..1a68a990705 100644
--- a/code/modules/awaymissions/mission_code/ruins/oldstation.dm
+++ b/code/modules/awaymissions/mission_code/ruins/oldstation.dm
@@ -369,7 +369,7 @@
 	name = "old cryogenics pod"
 	desc = "A humming cryo pod. You can barely recognise a security uniform underneath the built up ice. The machine is attempting to wake up its occupant."
 	mob_name = "a security officer"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	roundstart = FALSE
 	death = FALSE
@@ -394,7 +394,7 @@
 	name = "old cryogenics pod"
 	desc = "A humming cryo pod. You can barely recognise a medical uniform underneath the built up ice. The machine is attempting to wake up its occupant."
 	mob_name = "a medical doctor"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	roundstart = FALSE
 	death = FALSE
@@ -419,7 +419,7 @@
 	name = "old cryogenics pod"
 	desc = "A humming cryo pod. You can barely recognise an engineering uniform underneath the built up ice. The machine is attempting to wake up its occupant."
 	mob_name = "an engineer"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	roundstart = FALSE
 	death = FALSE
@@ -444,7 +444,7 @@
 	name = "old cryogenics pod"
 	desc = "A humming cryo pod. You can barely recognise a science uniform underneath the built up ice. The machine is attempting to wake up its occupant."
 	mob_name = "a scientist"
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper"
 	roundstart = FALSE
 	death = FALSE
@@ -467,7 +467,7 @@
 /obj/structure/showcase/machinery/oldpod
 	name = "damaged cryogenic pod"
 	desc = "A damaged cryogenic pod long since lost to time, including its former occupant..."
-	icon = 'icons/obj/Cryogenic2.dmi'
+	icon = 'icons/obj/cryogenic2.dmi'
 	icon_state = "sleeper-open"
 
 /obj/structure/showcase/machinery/oldpod/used
diff --git a/code/modules/awaymissions/mission_code/spacehotel.dm b/code/modules/awaymissions/mission_code/spacehotel.dm
index b14bfae0d1b..0328dea5b53 100644
--- a/code/modules/awaymissions/mission_code/spacehotel.dm
+++ b/code/modules/awaymissions/mission_code/spacehotel.dm
@@ -89,7 +89,7 @@
 // The door to a hotel room, but also metadata for the room itself
 /obj/machinery/door/unpowered/hotel_door
 	name = "Room Door"
-	icon = 'icons/obj/doors/Doorsand.dmi'
+	icon = 'icons/obj/doors/doorsand.dmi'
 	icon_state = "door_closed"
 	autoclose = 1
 	var/doorOpen = 'sound/machines/airlock_open.ogg'
diff --git a/code/modules/mob/living/silicon/ai/ai.dm b/code/modules/mob/living/silicon/ai/ai.dm
index 239fec3b246..8c7d2ea64b2 100644
--- a/code/modules/mob/living/silicon/ai/ai.dm
+++ b/code/modules/mob/living/silicon/ai/ai.dm
@@ -36,7 +36,7 @@ var/list/ai_verbs_default = list(
 
 /mob/living/silicon/ai
 	name = "AI"
-	icon = 'icons/mob/AI.dmi'//
+	icon = 'icons/mob/ai.dmi'//
 	icon_state = "ai"
 	move_resist = MOVE_FORCE_VERY_STRONG
 	density = 1
@@ -143,7 +143,7 @@ var/list/ai_verbs_default = list(
 	density = 1
 	loc = loc
 
-	holo_icon = getHologramIcon(icon('icons/mob/AI.dmi',"holo1"))
+	holo_icon = getHologramIcon(icon('icons/mob/ai.dmi',"holo1"))
 
 	proc_holder_list = new()
 
@@ -379,7 +379,7 @@ var/list/ai_verbs_default = list(
 		//if(icon_state == initial(icon_state))
 	var/icontype = ""
 	icontype = input("Select an icon!", "AI", null, null) in display_choices
-	icon = 'icons/mob/AI.dmi'	//reset this in case we were on a custom sprite and want to change to a standard one
+	icon = 'icons/mob/ai.dmi'	//reset this in case we were on a custom sprite and want to change to a standard one
 	switch(icontype)
 		if("Custom")
 			icon = 'icons/mob/custom_synthetic/custom-synthetic.dmi'	//set this here so we can use the custom_sprite
@@ -1007,13 +1007,13 @@ var/list/ai_verbs_default = list(
 				qdel(holo_icon)
 				switch(input)
 					if("default")
-						holo_icon = getHologramIcon(icon('icons/mob/AI.dmi',"holo1"))
+						holo_icon = getHologramIcon(icon('icons/mob/ai.dmi',"holo1"))
 					if("floating face")
-						holo_icon = getHologramIcon(icon('icons/mob/AI.dmi',"holo2"))
+						holo_icon = getHologramIcon(icon('icons/mob/ai.dmi',"holo2"))
 					if("xeno queen")
-						holo_icon = getHologramIcon(icon('icons/mob/AI.dmi',"holo3"))
+						holo_icon = getHologramIcon(icon('icons/mob/ai.dmi',"holo3"))
 					if("eldritch")
-						holo_icon = getHologramIcon(icon('icons/mob/AI.dmi',"holo4"))
+						holo_icon = getHologramIcon(icon('icons/mob/ai.dmi',"holo4"))
 					if("ancient machine")
 						holo_icon = getHologramIcon(icon('icons/mob/ancient_machine.dmi', "ancient_machine"))
 					if("custom")
@@ -1022,7 +1022,7 @@ var/list/ai_verbs_default = list(
 						else if("[ckey]-ai-holo" in icon_states('icons/mob/custom_synthetic/custom-synthetic64.dmi'))
 							holo_icon = getHologramIcon(icon('icons/mob/custom_synthetic/custom-synthetic64.dmi', "[ckey]-ai-holo"))
 						else
-							holo_icon = getHologramIcon(icon('icons/mob/AI.dmi',"holo1"))
+							holo_icon = getHologramIcon(icon('icons/mob/ai.dmi',"holo1"))
 
 	return
 
diff --git a/code/modules/mob/living/silicon/ai/freelook/eye.dm b/code/modules/mob/living/silicon/ai/freelook/eye.dm
index 98d010b878c..7344c6469c4 100644
--- a/code/modules/mob/living/silicon/ai/freelook/eye.dm
+++ b/code/modules/mob/living/silicon/ai/freelook/eye.dm
@@ -6,7 +6,7 @@
 /mob/camera/aiEye
 	name = "Inactive AI Eye"
 
-	icon = 'icons/mob/AI.dmi' //Allows ghosts to see what the AI is looking at.
+	icon = 'icons/mob/ai.dmi' //Allows ghosts to see what the AI is looking at.
 	icon_state = "eye"
 	alpha = 127
 	invisibility = SEE_INVISIBLE_OBSERVER
diff --git a/code/modules/mob/living/silicon/decoy/decoy.dm b/code/modules/mob/living/silicon/decoy/decoy.dm
index 916d77992bf..de6c372acfb 100644
--- a/code/modules/mob/living/silicon/decoy/decoy.dm
+++ b/code/modules/mob/living/silicon/decoy/decoy.dm
@@ -1,13 +1,13 @@
 /mob/living/silicon/decoy
 	name = "AI"
-	icon = 'icons/mob/AI.dmi'//
+	icon = 'icons/mob/ai.dmi'//
 	icon_state = "ai"
 	anchored = 1 // -- TLE
 	canmove = 0
 	a_intent = INTENT_HARM // This is apparently the only thing that stops other mobs walking through them as if they were thin air.
 
 /mob/living/silicon/decoy/New()
-	src.icon = 'icons/mob/AI.dmi'
+	src.icon = 'icons/mob/ai.dmi'
 	src.icon_state = "ai"
 	src.anchored = 1
 	src.canmove = 0
diff --git a/icons/Testing/Zone.dmi b/icons/Testing/zone.dmi
similarity index 100%
rename from icons/Testing/Zone.dmi
rename to icons/Testing/zone.dmi
diff --git a/icons/BadAss.dmi b/icons/badass.dmi
similarity index 100%
rename from icons/BadAss.dmi
rename to icons/badass.dmi
diff --git a/icons/effects/ss13_dark_alpha7_DEBUG.dmi b/icons/effects/ss13_dark_alpha7_debug.dmi
similarity index 100%
rename from icons/effects/ss13_dark_alpha7_DEBUG.dmi
rename to icons/effects/ss13_dark_alpha7_debug.dmi
diff --git a/icons/effects/Targeted.dmi b/icons/effects/targeted.dmi
similarity index 100%
rename from icons/effects/Targeted.dmi
rename to icons/effects/targeted.dmi
diff --git a/icons/effects/ULIcons.dmi b/icons/effects/ulicons.dmi
similarity index 100%
rename from icons/effects/ULIcons.dmi
rename to icons/effects/ulicons.dmi
diff --git a/icons/mob/AI.dmi b/icons/mob/ai.dmi
similarity index 100%
rename from icons/mob/AI.dmi
rename to icons/mob/ai.dmi
diff --git a/icons/obj/Cryogenic2.dmi b/icons/obj/cryogenic2.dmi
similarity index 100%
rename from icons/obj/Cryogenic2.dmi
rename to icons/obj/cryogenic2.dmi
diff --git a/icons/obj/doors/Door2x1glass.dmi b/icons/obj/doors/door2x1glass.dmi
similarity index 100%
rename from icons/obj/doors/Door2x1glass.dmi
rename to icons/obj/doors/door2x1glass.dmi
diff --git a/icons/obj/doors/Doorf.dmi b/icons/obj/doors/doorf.dmi
similarity index 100%
rename from icons/obj/doors/Doorf.dmi
rename to icons/obj/doors/doorf.dmi
diff --git a/icons/obj/doors/Doorfire.dmi b/icons/obj/doors/doorfire.dmi
similarity index 100%
rename from icons/obj/doors/Doorfire.dmi
rename to icons/obj/doors/doorfire.dmi
diff --git a/icons/obj/doors/Doorfireglass.dmi b/icons/obj/doors/doorfireglass.dmi
similarity index 100%
rename from icons/obj/doors/Doorfireglass.dmi
rename to icons/obj/doors/doorfireglass.dmi
diff --git a/icons/obj/doors/Doorgold.dmi b/icons/obj/doors/doorgold.dmi
similarity index 100%
rename from icons/obj/doors/Doorgold.dmi
rename to icons/obj/doors/doorgold.dmi
diff --git a/icons/obj/doors/DoorHazard.dmi b/icons/obj/doors/doorhazard.dmi
similarity index 100%
rename from icons/obj/doors/DoorHazard.dmi
rename to icons/obj/doors/doorhazard.dmi
diff --git a/icons/obj/doors/DoorHazard2x1.dmi b/icons/obj/doors/doorhazard2x1.dmi
similarity index 100%
rename from icons/obj/doors/DoorHazard2x1.dmi
rename to icons/obj/doors/doorhazard2x1.dmi
diff --git a/icons/obj/doors/DoorHazard3x1.dmi b/icons/obj/doors/doorhazard3x1.dmi
similarity index 100%
rename from icons/obj/doors/DoorHazard3x1.dmi
rename to icons/obj/doors/doorhazard3x1.dmi
diff --git a/icons/obj/doors/Doorsand.dmi b/icons/obj/doors/doorsand.dmi
similarity index 100%
rename from icons/obj/doors/Doorsand.dmi
rename to icons/obj/doors/doorsand.dmi
diff --git a/icons/obj/doors/edge_Doorfire.dmi b/icons/obj/doors/edge_doorfire.dmi
similarity index 100%
rename from icons/obj/doors/edge_Doorfire.dmi
rename to icons/obj/doors/edge_doorfire.dmi