diff --git a/src/mbgl/map/source.cpp b/src/mbgl/map/source.cpp
index b6a941b26..282fd3093 100644
--- a/src/mbgl/map/source.cpp
+++ b/src/mbgl/map/source.cpp
@@ -97,7 +97,7 @@ void SourceInfo::parseTileJSONProperties(const rapidjson::Value& value) {
 }
 
 std::string SourceInfo::tileURL(const Tile::ID& id, float pixelRatio) const {
-    std::string result = tiles[(id.x + id.y) % tiles.size()];
+    std::string result = tiles.at((id.x + id.y) % tiles.size());
     result = util::mapbox::normalizeTileURL(result, url, type);
     result = util::replaceTokens(result, [&](const std::string &token) -> std::string {
         if (token == "z") return util::toString(id.z);
diff --git a/src/mbgl/map/tile_data.cpp b/src/mbgl/map/tile_data.cpp
index 2675c0644..a2e485a24 100644
--- a/src/mbgl/map/tile_data.cpp
+++ b/src/mbgl/map/tile_data.cpp
@@ -30,9 +30,6 @@ const std::string TileData::toString() const {
 }
 
 void TileData::request(uv::worker &worker, float pixelRatio, std::function<void()> callback) {
-    if (source.tiles.empty())
-        return;
-
     std::string url = source.tileURL(id, pixelRatio);
     state = State::loading;