diff --git a/changelog.txt b/changelog.txt
index 9905a39b..201f096a 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -9,6 +9,7 @@ Date: ???
     - Fixed typos in cadaveric seed separation tech name.
     - Fixed that guano can't be set as a filter. (https://github.com/pyanodon/pybugreports/issues/412)
     - Fixed vrauk MK02+ duplication with turd path 2. (https://github.com/pyanodon/pybugreports/issues/406)
+    - Fixed improper pipe connections for simik dens (https://github.com/pyanodon/pybugreports/issues/404)
 ---------------------------------------------------------------------------------------------------
 Version: 2.1.21
 Date: 2024-2-2
diff --git a/prototypes/buildings/simik-den-mk01.lua b/prototypes/buildings/simik-den-mk01.lua
index 08cb74ee..0724cf27 100644
--- a/prototypes/buildings/simik-den-mk01.lua
+++ b/prototypes/buildings/simik-den-mk01.lua
@@ -244,7 +244,7 @@ ENTITY {
             pipe_picture = DATA.Pipes.pictures("assembling-machine-3", nil, {0.0, -0.88}, nil, nil),
             base_area = 10,
             base_level = -1,
-            pipe_connections = {{type = "input", position = {0.0, -8.5}}},
+            pipe_connections = {{type = "input", position = {0.5, -8.5}}, {type = "input", position = {-0.5, -8.5}}},
             secondary_draw_orders = { north = -1 }
         },
         off_when_no_fluid_recipe = true
diff --git a/prototypes/buildings/simik-den-mk02.lua b/prototypes/buildings/simik-den-mk02.lua
index d18ca92b..36d70c50 100644
--- a/prototypes/buildings/simik-den-mk02.lua
+++ b/prototypes/buildings/simik-den-mk02.lua
@@ -239,7 +239,7 @@ ENTITY {
             pipe_picture = DATA.Pipes.pictures("assembling-machine-3", nil, {0.0, -0.88}, nil, nil),
             base_area = 10,
             base_level = -1,
-            pipe_connections = {{type = "input", position = {0.0, -8.5}}},
+            pipe_connections = {{type = "input", position = {0.5, -8.5}}, {type = "input", position = {-0.5, -8.5}}},
             secondary_draw_orders = { north = -1 }
         },
         off_when_no_fluid_recipe = true
diff --git a/prototypes/buildings/simik-den-mk03.lua b/prototypes/buildings/simik-den-mk03.lua
index 0fecce42..5dbb15ef 100644
--- a/prototypes/buildings/simik-den-mk03.lua
+++ b/prototypes/buildings/simik-den-mk03.lua
@@ -239,7 +239,7 @@ ENTITY {
             pipe_picture = DATA.Pipes.pictures("assembling-machine-3", nil, {0.0, -0.88}, nil, nil),
             base_area = 10,
             base_level = -1,
-            pipe_connections = {{type = "input", position = {0.0, -8.5}}},
+            pipe_connections = {{type = "input", position = {0.5, -8.5}}, {type = "input", position = {-0.5, -8.5}}},
             secondary_draw_orders = { north = -1 }
         },
         off_when_no_fluid_recipe = true
diff --git a/prototypes/buildings/simik-den-mk04.lua b/prototypes/buildings/simik-den-mk04.lua
index d292388d..cc775a45 100644
--- a/prototypes/buildings/simik-den-mk04.lua
+++ b/prototypes/buildings/simik-den-mk04.lua
@@ -238,7 +238,7 @@ ENTITY {
             pipe_picture = DATA.Pipes.pictures("assembling-machine-3", nil, {0.0, -0.88}, nil, nil),
             base_area = 10,
             base_level = -1,
-            pipe_connections = {{type = "input", position = {0.0, -8.5}}},
+            pipe_connections = {{type = "input", position = {0.5, -8.5}}, {type = "input", position = {-0.5, -8.5}}},
             secondary_draw_orders = { north = -1 }
         },
         off_when_no_fluid_recipe = true