diff --git a/src/TiledArray/tensor/tensor.h b/src/TiledArray/tensor/tensor.h
index 171dac2eea..bf729e59d9 100644
--- a/src/TiledArray/tensor/tensor.h
+++ b/src/TiledArray/tensor/tensor.h
@@ -705,7 +705,7 @@ class Tensor {
   const_reference operator[](const Ordinal ord) const {
     TA_ASSERT(!this->empty());
     // can't distinguish between operator[](Index...) and operator[](ordinal)
-    // thus assume at_ordinal() if this->rank()==1
+    // thus insist on at_ordinal() if this->rank()==1
     TA_ASSERT(this->range_.rank() != 1 &&
               "use Tensor::operator[](index) or "
               "Tensor::at_ordinal(index_ordinal) if this->range().rank()==1");
@@ -726,7 +726,7 @@ class Tensor {
   reference operator[](const Ordinal ord) {
     TA_ASSERT(!this->empty());
     // can't distinguish between operator[](Index...) and operator[](ordinal)
-    // thus assume at_ordinal() if this->rank()==1
+    // thus insist on at_ordinal() if this->rank()==1
     TA_ASSERT(this->range_.rank() != 1 &&
               "use Tensor::operator[](index) or "
               "Tensor::at_ordinal(index_ordinal) if this->range().rank()==1");
@@ -848,7 +848,7 @@ class Tensor {
     TA_ASSERT(!this->empty());
     TA_ASSERT(this->nbatch() == 1);
     // can't distinguish between operator[](Index...) and operator[](ordinal)
-    // thus assume at_ordinal() if this->rank()==1
+    // thus insist on at_ordinal() if this->rank()==1
     TA_ASSERT(this->range_.rank() != 1 &&
               "use Tensor::operator()(index) or "
               "Tensor::at_ordinal(index_ordinal) if this->range().rank()==1");
@@ -869,7 +869,7 @@ class Tensor {
     TA_ASSERT(!this->empty());
     TA_ASSERT(this->nbatch() == 1);
     // can't distinguish between operator[](Index...) and operator[](ordinal)
-    // thus assume at_ordinal() if this->rank()==1
+    // thus insist on at_ordinal() if this->rank()==1
     TA_ASSERT(this->range_.rank() != 1 &&
               "use Tensor::operator()(index) or "
               "Tensor::at_ordinal(index_ordinal) if this->range().rank()==1");
@@ -960,6 +960,12 @@ class Tensor {
   const_reference operator()(const Index&... i) const {
     TA_ASSERT(!this->empty());
     TA_ASSERT(this->nbatch() == 1);
+    TA_ASSERT(this->range().rank() == sizeof...(Index));
+    // can't distinguish between operator()(Index...) and operator()(ordinal)
+    // thus insist on at_ordinal() if this->rank()==1
+    TA_ASSERT(this->range_.rank() != 1 &&
+              "use Tensor::operator()(index) or "
+              "Tensor::at_ordinal(index_ordinal) if this->range().rank()==1");
     using Int = std::common_type_t<Index...>;
     const auto iord = this->range_.ordinal(
         std::array<Int, sizeof...(Index)>{{static_cast<Int>(i)...}});
@@ -982,6 +988,12 @@ class Tensor {
   reference operator()(const Index&... i) {
     TA_ASSERT(!this->empty());
     TA_ASSERT(this->nbatch() == 1);
+    TA_ASSERT(this->range().rank() == sizeof...(Index));
+    // can't distinguish between operator()(Index...) and operator()(ordinal)
+    // thus insist on at_ordinal() if this->rank()==1
+    TA_ASSERT(this->range_.rank() != 1 &&
+              "use Tensor::operator()(index) or "
+              "Tensor::at_ordinal(index_ordinal) if this->range().rank()==1");
     using Int = std::common_type_t<Index...>;
     const auto iord = this->range_.ordinal(
         std::array<Int, sizeof...(Index)>{{static_cast<Int>(i)...}});
diff --git a/src/TiledArray/tile.h b/src/TiledArray/tile.h
index b8c62d95b8..39fca37d9e 100644
--- a/src/TiledArray/tile.h
+++ b/src/TiledArray/tile.h
@@ -250,6 +250,11 @@ class Tile {
             std::enable_if_t<std::is_integral<Ordinal>::value>* = nullptr>
   const_reference operator[](const Ordinal ord) const {
     TA_ASSERT(pimpl_);
+    // can't distinguish between operator[](Index...) and operator[](ordinal)
+    // thus insist on at_ordinal() if this->rank()==1
+    TA_ASSERT(this->range().rank() != 1 &&
+              "use Tile::operator[](index) or "
+              "Tile::at_ordinal(index_ordinal) if this->range().rank()==1");
     TA_ASSERT(tensor().range().includes_ordinal(ord));
     return tensor().data()[ord];
   }
@@ -264,6 +269,41 @@ class Tile {
   template <typename Ordinal,
             std::enable_if_t<std::is_integral<Ordinal>::value>* = nullptr>
   reference operator[](const Ordinal ord) {
+    TA_ASSERT(pimpl_);
+    // can't distinguish between operator[](Index...) and operator[](ordinal)
+    // thus insist on at_ordinal() if this->rank()==1
+    TA_ASSERT(this->range().rank() != 1 &&
+              "use Tile::operator[](index) or "
+              "Tile::at_ordinal(index_ordinal) if this->range().rank()==1");
+    TA_ASSERT(tensor().range().includes_ordinal(ord));
+    return tensor().data()[ord];
+  }
+
+  /// Const element accessor
+
+  /// \tparam Ordinal an integer type that represents an ordinal
+  /// \param[in] ord an ordinal index
+  /// \return Const reference to the element at position \c ord .
+  /// \note This asserts (using TA_ASSERT) that this is not empty and ord is
+  /// included in the range
+  template <typename Ordinal,
+            std::enable_if_t<std::is_integral<Ordinal>::value>* = nullptr>
+  const_reference at_ordinal(const Ordinal ord) const {
+    TA_ASSERT(pimpl_);
+    TA_ASSERT(tensor().range().includes_ordinal(ord));
+    return tensor().data()[ord];
+  }
+
+  /// Element accessor
+
+  /// \tparam Ordinal an integer type that represents an ordinal
+  /// \param[in] ord an ordinal index
+  /// \return Reference to the element at position \c ord .
+  /// \note This asserts (using TA_ASSERT) that this is not empty and ord is
+  /// included in the range
+  template <typename Ordinal,
+            std::enable_if_t<std::is_integral<Ordinal>::value>* = nullptr>
+  reference at_ordinal(const Ordinal ord) {
     TA_ASSERT(pimpl_);
     TA_ASSERT(tensor().range().includes_ordinal(ord));
     return tensor().data()[ord];
@@ -401,6 +441,12 @@ class Tile {
                        detail::is_integral_list<Index...>::value>* = nullptr>
   const_reference operator()(const Index&... i) const {
     TA_ASSERT(pimpl_);
+    TA_ASSERT(this->range().rank() == sizeof...(Index));
+    // can't distinguish between operator()(Index...) and operator()(ordinal)
+    // thus insist on at_ordinal() if this->rank()==1
+    TA_ASSERT(this->range().rank() != 1 &&
+              "use Tile::operator()(index) or "
+              "Tile::at_ordinal(index_ordinal) if this->range().rank()==1");
     TA_ASSERT(tensor().range().includes(i...));
     return tensor().data()[tensor().range().ordinal(i...)];
   }
@@ -417,6 +463,12 @@ class Tile {
                        detail::is_integral_list<Index...>::value>* = nullptr>
   reference operator()(const Index&... i) {
     TA_ASSERT(pimpl_);
+    TA_ASSERT(this->range().rank() == sizeof...(Index));
+    // can't distinguish between operator()(Index...) and operator()(ordinal)
+    // thus insist on at_ordinal() if this->rank()==1
+    TA_ASSERT(this->range().rank() != 1 &&
+              "use Tile::operator()(index) or "
+              "Tile::at_ordinal(index_ordinal) if this->range().rank()==1");
     TA_ASSERT(tensor().range().includes(i...));
     return tensor().data()[tensor().range().ordinal(i...)];
   }