diff --git a/include/rapidjson/internal/biginteger.h b/include/rapidjson/internal/biginteger.h
index f4d6d1282..4477cf5d1 100755
--- a/include/rapidjson/internal/biginteger.h
+++ b/include/rapidjson/internal/biginteger.h
@@ -54,8 +54,10 @@ class BigInteger {
     
     BigInteger& operator=(const BigInteger &rhs)
     {
-        count_ = rhs.count_;
-        std::memcpy(digits_, rhs.digits_, count_ * sizeof(Type));
+        if (this != &rhs) {
+            count_ = rhs.count_;
+            std::memcpy(digits_, rhs.digits_, count_ * sizeof(Type));
+        }
         return *this;
     }