diff --git a/src/map.cpp b/src/map.cpp
index 392ab8ab6c..a8023c9226 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -32,17 +32,14 @@ uint _map_tile_mask; ///< _map_size - 1 (to mask the mapsize)
 Tile *_m = NULL;          ///< Tiles of the map
 TileExtended *_me = NULL; ///< Extended Tiles of the map
 
-
 /**
- * (Re)allocates a map with the given dimension
+ * Validates whether a map with the given dimension is valid
  * @param size_x the width of the map along the NE/SW edge
  * @param size_y the 'height' of the map along the SE/NW edge
+ * @return true if valid, or false if not valid
  */
-void AllocateMap(uint size_x, uint size_y)
+bool ValidateMapSize(uint size_x, uint size_y)
 {
-	DEBUG(map, 2, "Min/max map size %d/%d, max map tiles %d", MIN_MAP_SIZE, MAX_MAP_SIZE, MAX_MAP_TILES);
-	DEBUG(map, 1, "Allocating map of size %dx%d", size_x, size_y);
-
 	/* Make sure that the map size is within the limits and that
 	 * size of both axes is a power of 2. */
 	if (size_x * size_y > MAX_MAP_TILES ||
@@ -50,6 +47,22 @@ void AllocateMap(uint size_x, uint size_y)
 			size_y < MIN_MAP_SIZE ||
 			(size_x & (size_x - 1)) != 0 ||
 			(size_y & (size_y - 1)) != 0) {
+		return false;
+	}
+	return true;
+}
+
+/**
+ * (Re)allocates a map with the given dimension
+ * @param size_x the width of the map along the NE/SW edge
+ * @param size_y the 'height' of the map along the SE/NW edge
+ */
+void AllocateMap(uint size_x, uint size_y)
+{
+	DEBUG(map, 2, "Min/max map size %d/%d, max map tiles %d", MIN_MAP_SIZE, MAX_MAP_SIZE, MAX_MAP_TILES);
+	DEBUG(map, 1, "Allocating map of size %dx%d", size_x, size_y);
+
+	if (!ValidateMapSize(size_x, size_y)) {
 		error("Invalid map size");
 	}
 
diff --git a/src/map_func.h b/src/map_func.h
index 9198c2cd1f..b390f0eaef 100644
--- a/src/map_func.h
+++ b/src/map_func.h
@@ -43,6 +43,7 @@ extern Tile *_m;
  */
 extern TileExtended *_me;
 
+bool ValidateMapSize(uint size_x, uint size_y);
 void AllocateMap(uint size_x, uint size_y);
 
 /**
diff --git a/src/saveload/extended_ver_sl.cpp b/src/saveload/extended_ver_sl.cpp
index 3f6b693f56..40aa560ce0 100644
--- a/src/saveload/extended_ver_sl.cpp
+++ b/src/saveload/extended_ver_sl.cpp
@@ -33,6 +33,7 @@
 #include "saveload.h"
 #include "extended_ver_sl.h"
 #include "../timetable.h"
+#include "../map_func.h"
 
 #include <vector>
 
@@ -62,6 +63,7 @@ const SlxiSubChunkInfo _sl_xv_sub_chunk_infos[] = {
 	{ XSLFI_VARIABLE_DAY_LENGTH,    XSCF_NULL,              1,                                    1, "variable_day_length",   NULL, NULL, NULL        },
 	{ XSLFI_ORDER_OCCUPANCY,        XSCF_NULL,              1,                                    1, "order_occupancy",       NULL, NULL, NULL        },
 	{ XSLFI_MORE_COND_ORDERS,       XSCF_NULL,              1,                                    1, "more_cond_orders",      NULL, NULL, NULL        },
+	{ XSLFI_EXTRA_LARGE_MAP,        XSCF_NULL,              0,                                    1, "extra_large_map",       NULL, NULL, NULL        },
 	{ XSLFI_NULL, XSCF_NULL, 0, 0, NULL, NULL, NULL, NULL },// This is the end marker
 };
 
@@ -125,6 +127,9 @@ void SlXvSetCurrentState()
 	for (; info->index != XSLFI_NULL; ++info) {
 		_sl_xv_feature_versions[info->index] = info->save_version;
 	}
+	if (MapSizeX() > 8192 || MapSizeY() > 8192) {
+		_sl_xv_feature_versions[XSLFI_EXTRA_LARGE_MAP] = 1;
+	}
 }
 
 /**
@@ -220,7 +225,6 @@ static void Save_SLXI()
 	SlXvSetCurrentState();
 
 	static const SaveLoad _xlsi_sub_chunk_desc[] = {
-		SLE_VAR(SlxiSubChunkInfo, save_version,   SLE_UINT16),
 		SLE_STR(SlxiSubChunkInfo, name,           SLE_STR, 0),
 		SLE_END()
 	};
@@ -234,9 +238,9 @@ static void Save_SLXI()
 	chunk_counts.resize(XSLFI_SIZE);
 	const SlxiSubChunkInfo *info = _sl_xv_sub_chunk_infos;
 	for (; info->index != XSLFI_NULL; ++info) {
-		if (info->save_version > 0) {
+		if (_sl_xv_feature_versions[info->index] > 0) {
 			item_count++;
-			length += 4;
+			length += 6;
 			length += SlCalcObjLength(info, _xlsi_sub_chunk_desc);
 			if (info->save_proc) {
 				uint32 extra_data_length = info->save_proc(info, true);
@@ -264,7 +268,8 @@ static void Save_SLXI()
 	// write data
 	info = _sl_xv_sub_chunk_infos;
 	for (; info->index != XSLFI_NULL; ++info) {
-		if (info->save_version > 0) {
+		uint16 save_version = _sl_xv_feature_versions[info->index];
+		if (save_version > 0) {
 			SlxiSubChunkFlags flags = info->flags;
 			assert(!(flags & (XSCF_EXTRA_DATA_PRESENT | XSCF_CHUNK_ID_LIST_PRESENT)));
 			uint32 extra_data_length = extra_data_lengths[info->index];
@@ -272,6 +277,7 @@ static void Save_SLXI()
 			if (extra_data_length > 0) flags |= XSCF_EXTRA_DATA_PRESENT;
 			if (chunk_count > 0) flags |= XSCF_CHUNK_ID_LIST_PRESENT;
 			SlWriteUint32(flags);
+			SlWriteUint16(save_version);
 			SlObject(const_cast<SlxiSubChunkInfo *>(info), _xlsi_sub_chunk_desc);
 
 			if (extra_data_length > 0) {
diff --git a/src/saveload/extended_ver_sl.h b/src/saveload/extended_ver_sl.h
index 7f010b59ec..86469e4a29 100644
--- a/src/saveload/extended_ver_sl.h
+++ b/src/saveload/extended_ver_sl.h
@@ -44,6 +44,7 @@ enum SlXvFeatureIndex {
 	XSLFI_TRAFFIC_LIGHTS,                         ///< This save game uses road traffic lights
 	XSLFI_RAIL_AGEING,                            ///< This save game uses the rail aging patch
 	XSLFI_SPRINGPP,                               ///< This is a SpringPP game, use this for loading some settings
+	XSLFI_EXTRA_LARGE_MAP,                        ///< Extra large map
 
 	XSLFI_SIZE,                                   ///< Total count of features, including null feature
 };
diff --git a/src/saveload/map_sl.cpp b/src/saveload/map_sl.cpp
index 86a185ca42..ee157ec17c 100644
--- a/src/saveload/map_sl.cpp
+++ b/src/saveload/map_sl.cpp
@@ -37,6 +37,9 @@ static void Save_MAPS()
 static void Load_MAPS()
 {
 	SlGlobList(_map_dimensions);
+	if (!ValidateMapSize(_map_dim_x, _map_dim_y)) {
+		SlErrorCorruptFmt("Invalid map size: %u x %u", _map_dim_x, _map_dim_y);
+	}
 	AllocateMap(_map_dim_x, _map_dim_y);
 }