diff --git a/gtsam/inference/Symbol.h b/gtsam/inference/Symbol.h
index 1d71ea3a6..bd04efc24 100644
--- a/gtsam/inference/Symbol.h
+++ b/gtsam/inference/Symbol.h
@@ -33,8 +33,8 @@ namespace gtsam {
  */
 class GTSAM_EXPORT Symbol {
 protected:
-  const unsigned char c_;
-  const std::uint64_t j_;
+  unsigned char c_;
+  std::uint64_t j_;
 
 public:
 
@@ -106,14 +106,6 @@ public:
     return comp != (Key)(*this);
   }
 
-  /** Explicit assignment */
-  Symbol& operator=(const Symbol& symbol2) {
-    if (&symbol2 != this) {
-      (unsigned char&) c_ = symbol2.c_;
-      (std::uint64_t&) j_ = symbol2.j_;
-    }
-    return *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