diff --git a/changelog.txt b/changelog.txt
index e5c1830..5abfc30 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -1,4 +1,16 @@
 ---------------------------------------------------------------------------------------------------
+Version: 0.4.5
+Date: 2022-08-18
+  Fixes:
+    - Fix multiple prerequisite issue
+---------------------------------------------------------------------------------------------------
+Version: 0.4.4
+Date: 2022-08-17
+  Fixes:
+    - SE: Disable matter recipes at start
+  Changes:
+    - Minor tech tree tweak for nanobots
+---------------------------------------------------------------------------------------------------
 Version: 0.4.3
 Date: 2022-08-16
   Features:
diff --git a/data-final-fixes.lua b/data-final-fixes.lua
index b98a912..3717753 100644
--- a/data-final-fixes.lua
+++ b/data-final-fixes.lua
@@ -110,6 +110,8 @@ if mods["aai-industry"] then
   util.set_tech_recipe("steam-power", {{"automation-science-pack", 1}})
 end
 
+util.add_prerequisite("nanobots", "electronics")
+
 if not mods.bzaluminum then
   util.replace_ingredients_prior_to("electronics", "electronic-circuit", "copper-cable", 2)
 end
diff --git a/data-util.lua b/data-util.lua
index 37e901a..b0fb612 100644
--- a/data-util.lua
+++ b/data-util.lua
@@ -89,6 +89,34 @@ function util.contains(table, sought)
   return false
 end
 
+
+-- se landfill
+-- params: ore, icon_size
+function util.se_landfill(params)
+  if mods["space-exploration"] then
+    if not params.icon_size then params.icon_size = 64 end
+    local lname="landfill-"..params.ore
+    data:extend({
+      {
+        type = "recipe",
+        icons = {
+          { icon = "__base__/graphics/icons/landfill.png", icon_size = 64, icon_mipmaps = 3 },
+          { icon = "__"..me.name.."__/graphics/icons/"..params.ore..".png", icon_size = params.icon_size, scale = 0.33*64/params.icon_size},
+        },
+        energy_required = 1,
+        enabled=false,
+        name = lname,
+        category = "hard-recycling",
+        order = "z-b-"..params.ore,
+        subgroup = "terrain",
+        result = "landfill",
+        ingredients = {{params.ore, 50}},
+      }
+    })
+    util.add_unlock("se-recycling-facility", lname)
+  end
+end
+
 -- se matter
 -- params: ore, energy_required, quant_out, quant_in, icon_size, stream_out
 function util.se_matter(params)
@@ -117,6 +145,7 @@ function util.se_matter(params)
            icon_size = 64, scale = 0.5},
         },
         energy_required = params.energy_required,
+        enabled = false,
         ingredients = {
           {sedata, 1},
           {type="fluid", name="se-particle-stream", amount=50},
@@ -136,6 +165,7 @@ function util.se_matter(params)
     if mods.Krastorio2 then
       local lname = params.ore.."-to-particle-stream"
       data:extend({
+        enabled = false,
         {
           type = "recipe",
           name = lname,
@@ -154,6 +184,7 @@ function util.se_matter(params)
              icon_size = 64, scale = 0.5},
           },
           energy_required = 30,
+          enabled = false,
           ingredients = {
             {"se-kr-matter-liberation-data", 1},
             {params.ore, params.quant_in},
@@ -221,6 +252,9 @@ function util.add_prerequisite(technology_name, prerequisite)
   local technology = data.raw.technology[technology_name]
   if technology and data.raw.technology[prerequisite] then
     if technology.prerequisites then
+      for i, pre in pairs(technology.prerequisites) do
+        if pre == prerequisite then return end
+      end
       table.insert(technology.prerequisites, prerequisite)
     else
       technology.prerequisites = {prerequisite}
diff --git a/info.json b/info.json
index ed7fa9c..876e1b6 100644
--- a/info.json
+++ b/info.json
@@ -1,6 +1,6 @@
 {
     "name": "bzcarbon",
-    "version": "0.4.3",
+    "version": "0.4.5",
     "factorio_version": "1.1",
     "title": "Graphite & Diamonds",
     "author": "Brevven",