diff --git a/src/mbgl/map/geometry_tile.hpp b/src/mbgl/map/geometry_tile.hpp
index a8105a500..3d5b677b8 100644
--- a/src/mbgl/map/geometry_tile.hpp
+++ b/src/mbgl/map/geometry_tile.hpp
@@ -85,12 +85,12 @@ std::ostream& operator<<(std::ostream&, const PositionedGlyph&);
 
 class GeometryTileLayer {
 public:
-    virtual const std::string getName() const = 0;
+    virtual const std::string& getName() const = 0;
     virtual uint32_t getExtent() const = 0;
-    virtual const std::vector<std::string> getKeys() const = 0;
-    virtual const std::unordered_map<std::string, uint32_t> getKeyIndex() const = 0;
-    virtual const std::vector<Value> getValues() const = 0;
-    virtual const std::map<std::string, std::map<Value, Shaping>> getShaping() const = 0;
+    virtual const std::vector<std::string>& getKeys() const = 0;
+    virtual const std::unordered_map<std::string, uint32_t>& getKeyIndex() const = 0;
+    virtual const std::vector<Value>& getValues() const = 0;
+    virtual const std::map<std::string, std::map<Value, Shaping>>& getShaping() const = 0;
     virtual std::unique_ptr<GeometryFilteredTileLayer> createFilteredTileLayer(const FilterExpression&) const = 0;
 };
 
diff --git a/src/mbgl/map/vector_tile.hpp b/src/mbgl/map/vector_tile.hpp
index 5fc6764b6..e2704a411 100644
--- a/src/mbgl/map/vector_tile.hpp
+++ b/src/mbgl/map/vector_tile.hpp
@@ -59,12 +59,12 @@ class VectorTileLayer : public GeometryTileLayer {
 public:
     VectorTileLayer(pbf);
 
-    virtual inline const std::string getName() const { return name; }
+    virtual inline const std::string& getName() const { return name; }
     virtual inline uint32_t getExtent() const { return extent; }
-    virtual inline const std::vector<std::string> getKeys() const { return keys; }
-    virtual inline const std::unordered_map<std::string, uint32_t> getKeyIndex() const { return key_index; }
-    virtual inline const std::vector<Value> getValues() const { return values; }
-    virtual inline const std::map<std::string, std::map<Value, Shaping>> getShaping() const { return shaping; }
+    virtual inline const std::vector<std::string>& getKeys() const { return keys; }
+    virtual inline const std::unordered_map<std::string, uint32_t>& getKeyIndex() const { return key_index; }
+    virtual inline const std::vector<Value>& getValues() const { return values; }
+    virtual inline const std::map<std::string, std::map<Value, Shaping>>& getShaping() const { return shaping; }
 
     virtual std::unique_ptr<GeometryFilteredTileLayer> createFilteredTileLayer(const FilterExpression&) const;