diff --git a/include/llmr/map/source.hpp b/include/llmr/map/source.hpp
index da2d87ae8..40b3bf4cf 100644
--- a/include/llmr/map/source.hpp
+++ b/include/llmr/map/source.hpp
@@ -69,7 +69,7 @@ private:
     const int32_t min_zoom;
     const int32_t max_zoom;
 
-    std::forward_list<Tile> tiles;
+    std::map<Tile::ID, std::unique_ptr<Tile>> tiles;
     std::map<Tile::ID, std::weak_ptr<TileData>> tile_data;
 };
 
diff --git a/src/map/source.cpp b/src/map/source.cpp
index 5571f74c7..a5985668f 100644
--- a/src/map/source.cpp
+++ b/src/map/source.cpp
@@ -34,7 +34,8 @@ bool Source::update() {
 }
 
 void Source::updateClipIDs(const std::map<Tile::ID, ClipID> &mapping) {
-    std::for_each(tiles.begin(), tiles.end(), [&mapping](Tile &tile) {
+    std::for_each(tiles.begin(), tiles.end(), [&mapping](std::pair<const Tile::ID, std::unique_ptr<Tile>> &pair) {
+        Tile &tile = *pair.second;
         auto it = mapping.find(tile.id);
         if (it != mapping.end()) {
             tile.clip = it->second;
@@ -48,7 +49,8 @@ size_t Source::prepareRender(const TransformState &transform) {
     if (!enabled) return 0;
 
     size_t masks = 0;
-    for (Tile& tile : tiles) {
+    for (std::pair<const Tile::ID, std::unique_ptr<Tile>> &pair : tiles) {
+        Tile &tile = *pair.second;
         gl::group group(util::sprintf<32>("mask %d/%d/%d", tile.id.z, tile.id.y, tile.id.z));
         transform.matrixFor(tile.matrix, tile.id);
         matrix::multiply(tile.matrix, painter.projMatrix, tile.matrix);
@@ -63,7 +65,8 @@ void Source::render(const LayerDescription& layer_desc, const BucketDescription
     if (!enabled) return;
 
     gl::group group(std::string("layer: ") + layer_desc.name);
-    for (const Tile& tile : tiles) {
+    for (std::pair<const Tile::ID, std::unique_ptr<Tile>> &pair : tiles) {
+        Tile &tile = *pair.second;
         if (tile.data && tile.data->state == TileData::State::parsed) {
             painter.renderTileLayer(tile, layer_desc);
         }
@@ -73,7 +76,8 @@ void Source::render(const LayerDescription& layer_desc, const BucketDescription
 void Source::finishRender() {
     if (!enabled) return;
 
-    for (const Tile& tile : tiles) {
+    for (std::pair<const Tile::ID, std::unique_ptr<Tile>> &pair : tiles) {
+        Tile &tile = *pair.second;
         painter.renderTileDebug(tile);
     }
 }
@@ -81,14 +85,18 @@ void Source::finishRender() {
 
 std::forward_list<Tile::ID> Source::getIDs() const {
     std::forward_list<Tile::ID> ptrs;
-    std::transform(tiles.begin(), tiles.end(), std::front_inserter(ptrs), [](const Tile &tile) {
+
+    std::transform(tiles.begin(), tiles.end(), std::front_inserter(ptrs), [](const std::pair<const Tile::ID, std::unique_ptr<Tile>> &pair) {
+        Tile &tile = *pair.second;
         return tile.id;
     });
     return ptrs;
 }
 
 TileData::State Source::hasTile(const Tile::ID& id) {
-    for (const Tile& tile : tiles) {
+    auto it = tiles.find(id);
+    if (it != tiles.end()) {
+        Tile &tile = *it->second;
         if (tile.id == id && tile.data) {
             return tile.data->state;
         }
@@ -104,8 +112,8 @@ TileData::State Source::addTile(const Tile::ID& id) {
         return state;
     }
 
-    tiles.emplace_front(id);
-    Tile& new_tile = tiles.front();
+    auto pos = tiles.emplace(id, std::make_unique<Tile>(id));
+    Tile& new_tile = *pos.first->second;
 
     // We couldn't find the tile in the list. Create a new one.
     // Try to find the associated TileData object.
@@ -249,31 +257,26 @@ bool Source::updateTiles() {
 
     // Remove tiles that we definitely don't need, i.e. tiles that are not on
     // the required list.
-    std::forward_list<Tile::ID> retain_data;
-    tiles.remove_if([&retain, &retain_data, &changed](const Tile & tile) {
+    std::set<Tile::ID> retain_data;
+    std::erase_if(tiles, [&retain, &retain_data, &changed](std::pair<const Tile::ID, std::unique_ptr<Tile>> &pair) {
+        Tile &tile = *pair.second;
         bool obsolete = std::find(retain.begin(), retain.end(), tile.id) == retain.end();
         if (obsolete) {
             changed = true;
         } else {
-            retain_data.push_front(tile.data->id);
+            retain_data.insert(tile.data->id);
         }
         return obsolete;
     });
 
-    // Sort tiles by zoom level, front to back.
-    // We're painting front-to-back, so we want to draw more detailed tiles first
-    // before filling in other parts with lower zoom levels.
-    tiles.sort([](const Tile & a, const Tile & b) {
-        return a.id.z < b.id.z;
-    });
-
     // Remove all the expired pointers from the set.
-    std::erase_if(tile_data, [&retain_data](const std::pair<Tile::ID, std::weak_ptr<TileData>>& pair) {
+    std::erase_if(tile_data, [&retain_data](std::pair<const Tile::ID, std::weak_ptr<TileData>> &pair) {
         const std::shared_ptr<TileData> tile = pair.second.lock();
         if (!tile) {
             return true;
         }
-        bool obsolete = std::find(retain_data.begin(), retain_data.end(), tile->id) == retain_data.end();
+
+        bool obsolete = retain_data.find(tile->id) == retain_data.end();
         if (obsolete) {
             tile->cancel();
             return true;