diff --git a/gtsam/nonlinear/Symbol.h b/gtsam/nonlinear/Symbol.h
index 945044492..18b5157bb 100644
--- a/gtsam/nonlinear/Symbol.h
+++ b/gtsam/nonlinear/Symbol.h
@@ -113,9 +113,15 @@ public:
   bool operator==(const Symbol& comp) const {
     return comp.c_ == c_ && comp.j_ == j_;
   }
+  bool operator==(Key comp) const {
+    return comp == (Key)(*this);
+  }
   bool operator!=(const Symbol& comp) const {
     return comp.c_ != c_ || comp.j_ != j_;
   }
+  bool operator!=(Key comp) const {
+    return comp != (Key)(*this);
+  }
 
   /** Return a filter function that returns true when evaluated on a Key whose
    * character (when converted to a Symbol) matches \c c.  Use this with the