diff --git a/src/Navaids/PositionedOctree.hxx b/src/Navaids/PositionedOctree.hxx
index 167f37a0d..1e04d6fd2 100644
--- a/src/Navaids/PositionedOctree.hxx
+++ b/src/Navaids/PositionedOctree.hxx
@@ -153,6 +153,7 @@ namespace Octree
     virtual void visitForLines(const SGVec3d& aPos, double aCutoff,
                          PolyLineList& aLines,
                          FindLinesDeque& aQ) const = 0;
+    virtual ~Node() {}
   protected:
     Node(const SGBoxd &aBox, int64_t aIdent) :
     _ident(aIdent),