diff --git a/src/object_gui.cpp b/src/object_gui.cpp
--- a/src/object_gui.cpp
+++ b/src/object_gui.cpp
@@ -565,20 +565,17 @@ public:
 	{
 		if (pt.x == -1) return;
 
-		switch (select_proc) {
-			default: NOT_REACHED();
-			case DDSP_BUILD_OBJECT:
-				if (!_settings_game.construction.freeform_edges) {
-					/* When end_tile is MP_VOID, the error tile will not be visible to the
-						* user. This happens when terraforming at the southern border. */
-					if (TileX(end_tile) == Map::MaxX()) end_tile += TileDiffXY(-1, 0);
-					if (TileY(end_tile) == Map::MaxY()) end_tile += TileDiffXY(0, -1);
-				}
-				const ObjectSpec *spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
-				Command<CMD_BUILD_OBJECT_AREA>::Post(STR_ERROR_CAN_T_BUILD_OBJECT, CcPlaySound_CONSTRUCTION_OTHER,
-					end_tile, start_tile, spec->Index(), _selected_object_view, (_ctrl_pressed ? true : false));
-				break;
+		assert(select_proc == DDSP_BUILD_OBJECT);
+
+		if (!_settings_game.construction.freeform_edges) {
+			/* When end_tile is MP_VOID, the error tile will not be visible to the
+			 * user. This happens when terraforming at the southern border. */
+			if (TileX(end_tile) == Map::MaxX()) end_tile += TileDiffXY(-1, 0);
+			if (TileY(end_tile) == Map::MaxY()) end_tile += TileDiffXY(0, -1);
 		}
+		const ObjectSpec *spec = ObjectClass::Get(_selected_object_class)->GetSpec(_selected_object_index);
+		Command<CMD_BUILD_OBJECT_AREA>::Post(STR_ERROR_CAN_T_BUILD_OBJECT, CcPlaySound_CONSTRUCTION_OTHER,
+			end_tile, start_tile, spec->Index(), _selected_object_view, (_ctrl_pressed ? true : false));
 	}
 
 	void OnPlaceObjectAbort() override