diff --git a/src/site/markdown/tutorials/direct-location-with-DEM.md b/src/site/markdown/tutorials/direct-location-with-DEM.md
index a962a9cdb204ececae39d1c9e2d5932dac009ba5..2b5739e1a22212241f948c223d2231d1afa5333d 100644
--- a/src/site/markdown/tutorials/direct-location-with-DEM.md
+++ b/src/site/markdown/tutorials/direct-location-with-DEM.md
@@ -39,6 +39,8 @@ The class `VolcanicConeElevationUpdater` implements the interface `TileUpdater`
 
 Here's the source code of the class `VolcanicConeElevationUpdater` :
 
+    import org.orekit.rugged.raster.TileUpdater;
+    import org.orekit.rugged.raster.UpdatableTile;
     import org.apache.commons.math3.util.FastMath;
     import org.orekit.bodies.GeodeticPoint;
     import org.orekit.rugged.errors.RuggedException;