diff --git a/src/saland/GameRegion.cpp b/src/saland/GameRegion.cpp
index 1f6f5c5..17b67e1 100644
--- a/src/saland/GameRegion.cpp
+++ b/src/saland/GameRegion.cpp
@@ -96,18 +96,25 @@ void GameRegion::SpawnPrefab(const Prefab& prefab, int destX, int destY) {
 			}
 		}
 	}
+	if (PrefabFootprintOverlapsPlaced(world.tm, destX, destY, prefab.width, prefab.height)) {
+		std::cout << "Do not spawn prefab " << prefab.name << "(" << destX << "," << destY << "), Overlaps an existing prefab\n";
+		return;
+	}
 	ApplyPrefab(world.tm, destX, destY, prefab);
 	this->world.init_physics(this->physicsBox);
 }
 
 bool GameRegion::RemovePrefabAtTile(int tileX, int tileY) {
+	bool removedAny = false;
 	PlacedPrefabInfo info;
-	if (!FindPlacedPrefabAtTile(world.tm, tileX, tileY, info)) {
-		return false;
+	while (FindPlacedPrefabAtTile(world.tm, tileX, tileY, info)) {
+		RemovePlacedPrefab(world.tm, info);
+		removedAny = true;
 	}
-	RemovePlacedPrefab(world.tm, info);
-	this->world.init_physics(this->physicsBox);
-	return true;
+	if (removedAny) {
+		this->world.init_physics(this->physicsBox);
+	}
+	return removedAny;
 }
 
 void GameRegion::SpawnItem(const ItemDef& def, float destX, float destY) {
diff --git a/src/saland/Prefabs.cpp b/src/saland/Prefabs.cpp
index da89690..c1bb6e7 100644
--- a/src/saland/Prefabs.cpp
+++ b/src/saland/Prefabs.cpp
@@ -41,6 +41,13 @@ static int GetLayerNumber(const sago::tiled::TileMap& tm, const char* name) {
 	return -1;
 }
 
+static void MarkerToTileRect(const sago::tiled::TileObject& o, int& destX, int& destY, int& width, int& height) {
+	destX = (o.x - 2) / 32;
+	destY = (o.y - 2) / 32;
+	width = (o.width + 4) / 32;
+	height = (o.height + 4) / 32;
+}
+
 static int32_t translate_tile(const sago::tiled::TileMap& dest, const sago::tiled::TileMap& source, int32_t source_tile) {
 	if (source_tile == 0) {
 		return 0;
@@ -137,10 +144,8 @@ bool FindPlacedPrefabAtTile(const sago::tiled::TileMap& tm, int tileX, int tileY
 			continue;
 		}
 		for (const auto& o : group.objects) {
-			int destX = (o.x - 2) / 32;
-			int destY = (o.y - 2) / 32;
-			int width = (o.width + 4) / 32;
-			int height = (o.height + 4) / 32;
+			int destX, destY, width, height;
+			MarkerToTileRect(o, destX, destY, width, height);
 			if (tileX >= destX && tileX < destX+width && tileY >= destY && tileY < destY+height) {
 				out.name = o.name;
 				out.destX = destX;
@@ -154,6 +159,23 @@ bool FindPlacedPrefabAtTile(const sago::tiled::TileMap& tm, int tileX, int tileY
 	return false;
 }
 
+bool PrefabFootprintOverlapsPlaced(const sago::tiled::TileMap& tm, int destX, int destY, int width, int height) {
+	for (const auto& group : tm.object_groups) {
+		if (group.name != "prefab_marking") {
+			continue;
+		}
+		for (const auto& o : group.objects) {
+			int mDestX, mDestY, mWidth, mHeight;
+			MarkerToTileRect(o, mDestX, mDestY, mWidth, mHeight);
+			bool disjoint = destX+width <= mDestX || mDestX+mWidth <= destX || destY+height <= mDestY || mDestY+mHeight <= destY;
+			if (!disjoint) {
+				return true;
+			}
+		}
+	}
+	return false;
+}
+
 void RemovePlacedPrefab(sago::tiled::TileMap& dest, const PlacedPrefabInfo& info) {
 	static const char* destLayers[] = {"prefab_ground_1", "blocking", "prefab_blocking_2", "prefab_overlay_1"};
 	for (const char* destLayer : destLayers) {
@@ -173,7 +195,9 @@ void RemovePlacedPrefab(sago::tiled::TileMap& dest, const PlacedPrefabInfo& info
 		}
 		auto& objects = group.objects;
 		objects.erase(std::remove_if(objects.begin(), objects.end(), [&info](const sago::tiled::TileObject& o) {
-			return o.name == info.name && (o.x - 2) / 32 == info.destX && (o.y - 2) / 32 == info.destY;
+			int destX, destY, width, height;
+			MarkerToTileRect(o, destX, destY, width, height);
+			return o.name == info.name && destX == info.destX && destY == info.destY;
 		}), objects.end());
 		break;
 	}
diff --git a/src/saland/Prefabs.hpp b/src/saland/Prefabs.hpp
index 6fd4b3b..0009fa5 100644
--- a/src/saland/Prefabs.hpp
+++ b/src/saland/Prefabs.hpp
@@ -68,6 +68,12 @@ struct PlacedPrefabInfo {
 bool FindPlacedPrefabAtTile(const sago::tiled::TileMap& tm, int tileX, int tileY, PlacedPrefabInfo& out);
 
 /**
+ * Returns true if a prefab footprint of the given size at (destX, destY) would overlap
+ * any already-placed prefab (tracked via "prefab_marking" objects).
+ */
+bool PrefabFootprintOverlapsPlaced(const sago::tiled::TileMap& tm, int destX, int destY, int width, int height);
+
+/**
  * Clears the tiles stamped by a previously placed prefab and removes its marking object.
  * Use FindPlacedPrefabAtTile to locate the prefab to remove.
  */