diff --git a/code/__defines/mobs.dm b/code/__defines/mobs.dm
index 19e5615291..9ebf60632c 100644
--- a/code/__defines/mobs.dm
+++ b/code/__defines/mobs.dm
@@ -158,6 +158,7 @@
 #define O_MOUTH    "mouth"
 #define O_EYES     "eyes"
 #define O_HEART    "heart"
+#define O_CELL     "cell"
 #define O_LUNGS    "lungs"
 #define O_BRAIN    "brain"
 #define O_LIVER    "liver"
diff --git a/code/modules/organs/subtypes/machine.dm b/code/modules/organs/subtypes/machine.dm
index 439e9f7b2e..b775f93a8e 100644
--- a/code/modules/organs/subtypes/machine.dm
+++ b/code/modules/organs/subtypes/machine.dm
@@ -2,7 +2,7 @@
 	name = "microbattery"
 	desc = "A small, powerful cell for use in fully prosthetic bodies."
 	icon_state = "scell"
-	organ_tag = "cell"
+	organ_tag = O_CELL
 	parent_organ = BP_TORSO
 	vital = 1
 
@@ -21,7 +21,7 @@
 // Used for an MMI or posibrain being installed into a human.
 /obj/item/organ/internal/mmi_holder
 	name = "brain interface"
-	organ_tag = "brain"
+	organ_tag = O_BRAIN
 	parent_organ = BP_HEAD
 	vital = 1
 	var/brain_type = /obj/item/device/mmi
diff --git a/code/modules/research/prosfab_designs.dm b/code/modules/research/prosfab_designs.dm
index f26c66bc9a..38b00c5f96 100644
--- a/code/modules/research/prosfab_designs.dm
+++ b/code/modules/research/prosfab_designs.dm
@@ -156,6 +156,38 @@
 	materials = list(DEFAULT_WALL_MATERIAL = 5625, "glass" = 5625)
 //	req_tech = list(TECH_ENGINEERING = 2, TECH_MATERIAL = 2)
 
+/datum/design/item/prosfab/pros/heart
+	name = "Prosthetic heart"
+	id = "pros_heart"
+	build_path = /obj/item/organ/internal/heart
+	time = 15
+	materials = list(DEFAULT_WALL_MATERIAL = 5625, "glass" = 1000)
+//	req_tech = list(TECH_ENGINEERING = 2, TECH_MATERIAL = 2)
+
+/datum/design/item/prosfab/pros/lungs
+	name = "Prosthetic lungs"
+	id = "pros_lung"
+	build_path = /obj/item/organ/internal/lungs
+	time = 15
+	materials = list(DEFAULT_WALL_MATERIAL = 5625, "glass" = 1000)
+//	req_tech = list(TECH_ENGINEERING = 2, TECH_MATERIAL = 2)
+
+/datum/design/item/prosfab/pros/liver
+	name = "Prosthetic liver"
+	id = "pros_liver"
+	build_path = /obj/item/organ/internal/liver
+	time = 15
+	materials = list(DEFAULT_WALL_MATERIAL = 5625, "glass" = 1000)
+//	req_tech = list(TECH_ENGINEERING = 2, TECH_MATERIAL = 2)
+
+/datum/design/item/prosfab/pros/kidneys
+	name = "Prosthetic liver"
+	id = "pros_kidney"
+	build_path = /obj/item/organ/internal/kidneys
+	time = 15
+	materials = list(DEFAULT_WALL_MATERIAL = 5625, "glass" = 1000)
+//	req_tech = list(TECH_ENGINEERING = 2, TECH_MATERIAL = 2)
+
 //////////////////// Cyborg Parts ////////////////////
 /datum/design/item/prosfab/cyborg
 	category = "Cyborg Parts"