diff --git a/core/src/mindustry/world/blocks/distribution/Duct.java b/core/src/mindustry/world/blocks/distribution/Duct.java
index 735bf222b3..bfb0147f82 100644
--- a/core/src/mindustry/world/blocks/distribution/Duct.java
+++ b/core/src/mindustry/world/blocks/distribution/Duct.java
@@ -76,7 +76,7 @@ public class Duct extends Block implements Autotiler{
             || ((!otherblock.rotatedOutput(otherx, othery) && Edges.getFacingEdge(otherblock, otherx, othery, tile) != null &&
             Edges.getFacingEdge(otherblock, otherx, othery, tile).relativeTo(tile) == rotation) ||
 
-            ((otherblock.rotatedOutput(otherx, othery)) && Point2.equals(otherx + Geometry.d4(otherrot).x, othery + Geometry.d4(otherrot).y, tile.x, tile.y)));
+            ((otherblock.rotatedOutput(otherx, othery)) && (otherblock instanceof Duct) && Point2.equals(otherx + Geometry.d4(otherrot).x, othery + Geometry.d4(otherrot).y, tile.x, tile.y)));
     }
 
     @Override