diff --git a/lib/mapping/CMap.cpp b/lib/mapping/CMap.cpp
index e4c23d054..93c5fab2e 100644
--- a/lib/mapping/CMap.cpp
+++ b/lib/mapping/CMap.cpp
@@ -234,7 +234,7 @@ CMapHeader::~CMapHeader()
 CMap::CMap()
 	: checksum(0), grailPos(-1, -1, -1), grailRadius(0), terrain(nullptr),
 	guardingCreaturePositions(nullptr),
-	uid_counter(0)
+	uidCounter(0)
 {
 	allHeroes.resize(allowedHeroes.size());
 	allowedAbilities = VLC->skillh->getDefaultAllowed();
@@ -608,7 +608,7 @@ void CMap::setUniqueInstanceName(CGObjectInstance* obj)
 {
 	//this gives object unique name even if objects are removed later
 
-	auto uid = uid_counter++;
+	auto uid = uidCounter++;
 
 	boost::format fmt("%s_%d");
 	fmt % obj->typeName % uid;
diff --git a/lib/mapping/CMap.h b/lib/mapping/CMap.h
index dff87aa20..dd7f8bdfe 100644
--- a/lib/mapping/CMap.h
+++ b/lib/mapping/CMap.h
@@ -412,7 +412,7 @@ public:
 private:
 	/// a 3-dimensional array of terrain tiles, access is as follows: x, y, level. where level=1 is underground
 	TerrainTile*** terrain;
-	si32 uid_counter; //TODO: initialize when loading an old map
+	si32 uidCounter; //TODO: initialize when loading an old map
 
 public:
 	template <typename Handler>
@@ -490,6 +490,14 @@ public:
 		h & CGTownInstance::universitySkills;
 
 		h & instanceNames;
-		h & uid_counter;
+
+		if (!h.saving && formatVersion < 804)
+		{
+			uidCounter = objects.size();
+		}
+		else
+		{
+			h & uidCounter;
+		}
 	}
 };
diff --git a/lib/serializer/CSerializer.h b/lib/serializer/CSerializer.h
index e07e48d04..cb1f6af17 100644
--- a/lib/serializer/CSerializer.h
+++ b/lib/serializer/CSerializer.h
@@ -12,7 +12,7 @@
 #include "../ConstTransitivePtr.h"
 #include "../GameConstants.h"
 
-const ui32 SERIALIZATION_VERSION = 803;
+const ui32 SERIALIZATION_VERSION = 804;
 const ui32 MINIMAL_SERIALIZATION_VERSION = 803;
 const std::string SAVEGAME_MAGIC = "VCMISVG";