diff --git a/core/src/mindustry/editor/MapEditor.java b/core/src/mindustry/editor/MapEditor.java
index 8c743ad11f..6e9ceeb640 100644
--- a/core/src/mindustry/editor/MapEditor.java
+++ b/core/src/mindustry/editor/MapEditor.java
@@ -124,7 +124,9 @@ public class MapEditor{
         if(drawBlock.isMultiblock()){
             x = Mathf.clamp(x, (drawBlock.size - 1) / 2, width() - drawBlock.size / 2 - 1);
             y = Mathf.clamp(y, (drawBlock.size - 1) / 2, height() - drawBlock.size / 2 - 1);
-            tile(x, y).setBlock(drawBlock, drawTeam, 0);
+            if(!hasOverlap(x, y)){
+                tile(x, y).setBlock(drawBlock, drawTeam, 0);
+            }
         }else{
             boolean isFloor = drawBlock.isFloor() && drawBlock != Blocks.air;
 
@@ -152,6 +154,33 @@ public class MapEditor{
         }
     }
 
+    boolean hasOverlap(int x, int y){
+        Tile tile = world.tile(x, y);
+        //allow direct replacement of blocks of the same size
+        if(tile != null && tile.isCenter() && tile.block() != drawBlock && tile.block().size == drawBlock.size){
+            return false;
+        }
+
+        //else, check for overlap
+        int offsetx = -(drawBlock.size - 1) / 2;
+        int offsety = -(drawBlock.size - 1) / 2;
+        for(int dx = 0; dx < drawBlock.size; dx++){
+            for(int dy = 0; dy < drawBlock.size; dy++){
+                int worldx = dx + offsetx + x;
+                int worldy = dy + offsety + y;
+                if(!(worldx == x && worldy == y)){
+                    Tile other = world.tile(worldx, worldy);
+
+                    if(other != null && other.block().isMultiblock()){
+                        return true;
+                    }
+                }
+            }
+        }
+
+        return false;
+    }
+
     public void drawCircle(int x, int y, Cons<Tile> drawer){
         for(int rx = -brushSize; rx <= brushSize; rx++){
             for(int ry = -brushSize; ry <= brushSize; ry++){
diff --git a/core/src/mindustry/game/Schematic.java b/core/src/mindustry/game/Schematic.java
index 030b00cc78..9e798af72b 100644
--- a/core/src/mindustry/game/Schematic.java
+++ b/core/src/mindustry/game/Schematic.java
@@ -49,9 +49,9 @@ public class Schematic implements Publishable, Comparable<Schematic>{
     }
 
     public @NonNull CoreBlock findCore(){
-        CoreBlock block = (CoreBlock)tiles.find(s -> s.block instanceof CoreBlock).block;
-        if(block == null) throw new IllegalArgumentException("Schematic is missing a core!");
-        return block;
+        Stile tile = tiles.find(s -> s.block instanceof CoreBlock);
+        if(tile == null) throw new IllegalArgumentException("Schematic is missing a core!");
+        return (CoreBlock)tile.block;
     }
 
     public String name(){
diff --git a/core/src/mindustry/input/InputHandler.java b/core/src/mindustry/input/InputHandler.java
index b890eda45c..cedc02046c 100644
--- a/core/src/mindustry/input/InputHandler.java
+++ b/core/src/mindustry/input/InputHandler.java
@@ -50,13 +50,13 @@ public abstract class InputHandler implements InputProcessor, GestureListener{
 
     public final OverlayFragment frag = new OverlayFragment();
 
-    public Block block;
+    public @Nullable Block block;
     public boolean overrideLineRotation;
     public int rotation;
     public boolean droppingItem;
     public Group uiGroup;
     public boolean isShooting, isBuilding = true, buildWasAutoPaused = false;
-    public UnitType controlledType;
+    public @Nullable UnitType controlledType;
 
     protected @Nullable Schematic lastSchematic;
     protected GestureDetector detector;
@@ -510,7 +510,7 @@ public abstract class InputHandler implements InputProcessor, GestureListener{
 
         if(request.block.saveConfig && request.block.lastConfig != null){
             Object conf = request.config;
-            request.config = block.lastConfig;
+            request.config = request.block.lastConfig;
             request.block.drawRequestConfig(request, allRequests());
             request.config = conf;
         }