diff --git a/BGL/include/CGAL/boost/graph/graph_traits_HalfedgeDS.h b/BGL/include/CGAL/boost/graph/graph_traits_HalfedgeDS.h
index 7689590e2e1..eb492850d38 100644
--- a/BGL/include/CGAL/boost/graph/graph_traits_HalfedgeDS.h
+++ b/BGL/include/CGAL/boost/graph/graph_traits_HalfedgeDS.h
@@ -126,6 +126,17 @@ public:
     ++*this;
     return tmp;
   }
+
+  Self& operator--() {
+    --nt;
+    return *this;
+  }
+
+  Self  operator--(int) {
+    Self tmp = *this;
+    --*this;
+    return tmp;
+  }
 };
 
 template < class HDS >
@@ -197,6 +208,17 @@ public:
     ++*this;
     return tmp;
   }
+
+  Self& operator--() {
+    --nt;
+    return *this;
+  }
+
+  Self  operator--(int) {
+    Self tmp = *this;
+    --*this;
+    return tmp;
+  }
 };
 
 template < class HDS >
diff --git a/BGL/include/CGAL/boost/graph/graph_traits_Triangulation_2.h b/BGL/include/CGAL/boost/graph/graph_traits_Triangulation_2.h
index c63da2e0be4..39b3d5bff11 100644
--- a/BGL/include/CGAL/boost/graph/graph_traits_Triangulation_2.h
+++ b/BGL/include/CGAL/boost/graph/graph_traits_Triangulation_2.h
@@ -176,6 +176,17 @@ public:
     ++*this;
     return tmp;
   }
+
+  Self& operator--() {
+    --nt;
+    return *this;
+  }
+
+  Self  operator--(int) {
+    Self tmp = *this;
+    --*this;
+    return tmp;
+  }
 };