diff --git a/features/eid_repentogon.lua b/features/eid_repentogon.lua
index 25501139..3b98c5bc 100644
--- a/features/eid_repentogon.lua
+++ b/features/eid_repentogon.lua
@@ -1,6 +1,20 @@
 if not REPENTOGON then
 	return
 end
+
+-- Backwards compatibility for Repentogon on older isaac versions--
+
+-- Remove Necromancer transformation, as it doesnt exist in Version 1.9.7.12
+-- The following removes the data from EID, to prevent errors
+EID.TransformationData[tostring(EID.TRANSFORMATION.NECROMANCER)] = nil
+EID.TRANSFORMATION["NECROMANCER"] = nil
+-- remove Necromancer transformations from items that grant them
+EID.EntityTransformations["5.100.35"] = "12"	-- The Necronomicon: Bookworm, Necromancer
+EID.EntityTransformations["5.100.262"] = nil	-- Missing Page 2: Necromancer
+EID.EntityTransformations["5.350.48"] = nil	-- A Missing Page: Necromancer
+
+
+
 ---@diagnostic disable: duplicate-set-field
 local game = Game()
 local maxVanillaItemID = CollectibleType.NUM_COLLECTIBLES -- sanity backup