diff --git a/include/mvPolynomial/mvPolynomial.hpp b/include/mvPolynomial/mvPolynomial.hpp
index 2c993f1..c574bba 100644
--- a/include/mvPolynomial/mvPolynomial.hpp
+++ b/include/mvPolynomial/mvPolynomial.hpp
@@ -151,6 +151,7 @@ class MVPolynomial final {
       : index2value_(std::move(m.index2value_), a) {}
 
   MVPolynomial& operator=(std::initializer_list<value_type> l) {
+    index2value_.clear();
     index2value_.insert(l.begin(), l.end());
     CheckSelfIndexes();
     return *this;
@@ -188,13 +189,6 @@ class MVPolynomial final {
   mapped_type& operator[](const key_type& index) { return index2value_[index]; }
   mapped_type& operator[](key_type&& index) { return index2value_[index]; }
 
-  const mapped_type& operator[](const key_type& index) const {
-    return const_cast<MVPolynomial*>(this)->operator[](index);
-  }
-  const mapped_type& operator[](key_type&& index) const {
-    return const_cast<MVPolynomial*>(this)->operator[](index);
-  }
-
   mapped_type&       at(const key_type& i) { return index2value_.at(i); }
   const mapped_type& at(const key_type& i) const { return index2value_.at(i); }
 
@@ -371,10 +365,9 @@ class MVPolynomial final {
 
   MVPolynomial& operator*=(mapped_type r) {
     auto idx = index_type::Zero();
-    if (contains(idx)) {
-      (*this)[idx] *= r;
-    } else {
-      (*this)[idx] = r;
+    for (auto& index_and_coeff : *this) {
+      auto& coeff = index_and_coeff.second;
+      coeff *= 2;
     }
     return *this;
   }