diff --git a/others/large_number.h b/others/large_number.h
index 6d117d9dd..8a6afcaa4 100644
--- a/others/large_number.h
+++ b/others/large_number.h
@@ -239,6 +239,14 @@ public:
         return a;
     }
 
+    /**
+     * assignment operator
+     **/
+    void operator=(const large_number &b)
+    {
+        _digits = b._digits;
+    }
+
     /**
      * operator overload to increment
      **/