Switch from 'index' to 'ptr'
diff --git a/include/cxx.h b/include/cxx.h
index d19e318..de0e315 100644
--- a/include/cxx.h
+++ b/include/cxx.h
@@ -540,8 +540,8 @@
 template <typename T>
 T &Slice<T>::operator[](std::size_t n) const noexcept {
   assert(n < this->size());
-  auto index = static_cast<char *>(slicePtr(this)) + size_of<T>() * n;
-  return *reinterpret_cast<T *>(index);
+  auto ptr = static_cast<char *>(slicePtr(this)) + size_of<T>() * n;
+  return *reinterpret_cast<T *>(ptr);
 }
 
 template <typename T>
@@ -579,8 +579,8 @@
 template <typename T>
 typename Slice<T>::iterator::reference Slice<T>::iterator::operator[](
     typename Slice<T>::iterator::difference_type n) const noexcept {
-  auto index = static_cast<char *>(this->pos) + this->stride * n;
-  return *reinterpret_cast<T *>(index);
+  auto ptr = static_cast<char *>(this->pos) + this->stride * n;
+  return *reinterpret_cast<T *>(ptr);
 }
 
 template <typename T>