diff --git a/Engine/game/savegame_v321.cpp b/Engine/game/savegame_v321.cpp
index 117f5575f99..b6653c00a3d 100644
--- a/Engine/game/savegame_v321.cpp
+++ b/Engine/game/savegame_v321.cpp
@@ -350,10 +350,9 @@ static void restore_game_ambientsounds(Stream *in, RestoredData &r_data)
     }
 }
 
-static void ReadOverlays_Aligned(Stream *in, std::vector<bool> &has_bitmap, size_t num_overs)
+static void ReadOverlays_Aligned(Stream *in, std::vector<int> &has_bitmap, size_t num_overs)
 {
     AlignedStream align_s(in, Common::kAligned_Read);
-    has_bitmap.resize(num_overs);
     // Remember that overlay indexes may be non-sequential
     auto &overs = get_overlays();
     for (size_t i = 0; i < num_overs; ++i)
@@ -365,12 +364,10 @@ static void ReadOverlays_Aligned(Stream *in, std::vector<bool> &has_bitmap, size
         if (over.type < 0)
             continue; // safety abort
         if (overs.size() <= static_cast<uint32_t>(over.type))
-        {
             overs.resize(over.type + 1);
-            has_bitmap.resize(over.type + 1);
-        }
         overs[over.type] = std::move(over);
-        has_bitmap[over.type] = has_bm;
+        if (has_bm)
+            has_bitmap.push_back(over.type);
     }
 }
 
@@ -381,11 +378,10 @@ static void restore_game_overlays(Stream *in, RestoredData &r_data)
     // the vector may be resized during read
     auto &overs = get_overlays();
     overs.resize(num_overs);
-    std::vector<bool> has_bitmap(num_overs);
+    std::vector<int> has_bitmap;
     ReadOverlays_Aligned(in, has_bitmap, num_overs);
-    for (size_t i = 0; i < overs.size(); ++i) {
-        if (has_bitmap[i])
-            r_data.OverlayImages[i].reset(read_serialized_bitmap(in));
+    for (auto over_id : has_bitmap) {
+        r_data.OverlayImages[over_id].reset(read_serialized_bitmap(in));
     }
 }