diff --git a/include/sdf/Sky.hh b/include/sdf/Sky.hh
index ab1f21922..8bb76a5ae 100644
--- a/include/sdf/Sky.hh
+++ b/include/sdf/Sky.hh
@@ -103,7 +103,7 @@ namespace sdf
 
     /// \brief Get the skybox texture URI.
     /// \return The URI of the skybox texture.
-    public: std::string CubemapUri() const;
+    public: const std::string &CubemapUri() const;
 
     /// \brief Set the skybox texture URI.
     /// \param[in] _uri The URI of the skybox texture.
diff --git a/src/Sky.cc b/src/Sky.cc
index 901316ad5..a97ae0242 100644
--- a/src/Sky.cc
+++ b/src/Sky.cc
@@ -158,7 +158,7 @@ void Sky::SetCloudAmbient(const ignition::math::Color &_ambient)
 }
 
 //////////////////////////////////////////////////
-std::string Sky::CubemapUri() const
+const std::string &Sky::CubemapUri() const
 {
   return this->dataPtr->cubemapUri;
 }