diff --git a/apps/expression_editor/controller.cpp b/apps/expression_editor/controller.cpp
index 052815e49..8e9c77078 100644
--- a/apps/expression_editor/controller.cpp
+++ b/apps/expression_editor/controller.cpp
@@ -118,7 +118,7 @@ ExpressionLayout * Controller::handleAddEvent(Ion::Events::Event event) {
     return m_cursor.addEmptyPowerLayout();
   }
   if (event == Ion::Events::Sqrt) {
-    return m_cursor.addEmptyRootLayout();
+    return m_cursor.addEmptySquareRootLayout();
   }
   if (event == Ion::Events::Square) {
     return m_cursor.addEmptySquarePowerLayout();
diff --git a/poincare/include/poincare/expression_layout_cursor.h b/poincare/include/poincare/expression_layout_cursor.h
index 76b335f1c..779cd9318 100644
--- a/poincare/include/poincare/expression_layout_cursor.h
+++ b/poincare/include/poincare/expression_layout_cursor.h
@@ -44,7 +44,7 @@ public:
   ExpressionLayout * addFractionLayoutAndCollapseBrothers();
   ExpressionLayout * addEmptyLogarithmLayout();
   ExpressionLayout * addEmptyPowerLayout();
-  ExpressionLayout * addEmptyRootLayout();
+  ExpressionLayout * addEmptySquareRootLayout();
   ExpressionLayout * addEmptySquarePowerLayout();
   ExpressionLayout * addXNTCharLayout();
   ExpressionLayout * insertText(const char * text);
diff --git a/poincare/src/expression_layout_cursor.cpp b/poincare/src/expression_layout_cursor.cpp
index c22d3430b..1070b4167 100644
--- a/poincare/src/expression_layout_cursor.cpp
+++ b/poincare/src/expression_layout_cursor.cpp
@@ -127,10 +127,9 @@ ExpressionLayout * ExpressionLayoutCursor::addEmptyPowerLayout() {
   return child1;
 }
 
-ExpressionLayout * ExpressionLayoutCursor::addEmptyRootLayout() {
+ExpressionLayout * ExpressionLayoutCursor::addEmptySquareRootLayout() {
   EmptyVisibleLayout * child1 = new EmptyVisibleLayout();
-  EmptyVisibleLayout * child2 = new EmptyVisibleLayout();
-  NthRootLayout * newChild = new NthRootLayout(child1, child2, false);
+  NthRootLayout * newChild = new NthRootLayout(child1, false);
   m_pointedExpressionLayout->addBrother(this, newChild);
   setPointedExpressionLayout(child1);
   setPosition(ExpressionLayoutCursor::Position::Right);
diff --git a/poincare/src/layout/nth_root_layout.cpp b/poincare/src/layout/nth_root_layout.cpp
index 8d8ab0aa1..8831869c7 100644
--- a/poincare/src/layout/nth_root_layout.cpp
+++ b/poincare/src/layout/nth_root_layout.cpp
@@ -17,14 +17,18 @@ const uint8_t radixPixel[NthRootLayout::k_leftRadixHeight][NthRootLayout::k_left
 };
 
 ExpressionLayout * NthRootLayout::clone() const {
-  NthRootLayout * layout = new NthRootLayout(const_cast<NthRootLayout *>(this)->radicandLayout(), const_cast<NthRootLayout *>(this)->indexLayout(), true);
-  return layout;
+  if (numberOfChildren() == 1) {
+    return new NthRootLayout(const_cast<NthRootLayout *>(this)->radicandLayout(), true);
+  }
+  assert(numberOfChildren() == 2);
+  return new NthRootLayout(const_cast<NthRootLayout *>(this)->radicandLayout(), const_cast<NthRootLayout *>(this)->indexLayout(), true);
 }
 
 void NthRootLayout::backspaceAtCursor(ExpressionLayoutCursor * cursor) {
   // Case: Left the index.
   // Move Left.
-  if (cursor->position() == ExpressionLayoutCursor::Position::Left
+  if (indexLayout()
+      && cursor->position() == ExpressionLayoutCursor::Position::Left
       && cursor->pointedExpressionLayout() == indexLayout())
   {
     cursor->setPointedExpressionLayout(this);
@@ -64,7 +68,7 @@ void NthRootLayout::backspaceAtCursor(ExpressionLayoutCursor * cursor) {
   }
   // Case: Left.
   // Ask the parent.
-  assert(cursor->position() ==ExpressionLayoutCursor::Position::Left);
+  assert(cursor->position() == ExpressionLayoutCursor::Position::Left);
   if (m_parent) {
     return m_parent->backspaceAtCursor(cursor);
   }
@@ -155,20 +159,20 @@ bool NthRootLayout::moveRight(ExpressionLayoutCursor * cursor) {
 
 bool NthRootLayout::moveUp(ExpressionLayoutCursor * cursor, ExpressionLayout * previousLayout, ExpressionLayout * previousPreviousLayout) {
   // If the cursor is Left of the radicand, move it to the index.
-  if (radicandLayout()
+  if (indexLayout()
+      && radicandLayout()
       && previousLayout == radicandLayout()
       && cursor->positionIsEquivalentTo(radicandLayout(), ExpressionLayoutCursor::Position::Left))
   {
-    assert(indexLayout() != nullptr);
     cursor->setPointedExpressionLayout(indexLayout());
     cursor->setPosition(ExpressionLayoutCursor::Position::Right);
     return true;
   }
   // If the cursor is Left, move it to the index.
-  if (cursor->pointedExpressionLayout() == this
+  if (indexLayout()
+      && cursor->pointedExpressionLayout() == this
       && cursor->position() == ExpressionLayoutCursor::Position::Left)
   {
-    assert(indexLayout() != nullptr);
     cursor->setPointedExpressionLayout(indexLayout());
     cursor->setPosition(ExpressionLayoutCursor::Position::Left);
     return true;
@@ -260,12 +264,12 @@ KDPoint NthRootLayout::positionOfChild(ExpressionLayout * child) {
   KDCoordinate x = 0;
   KDCoordinate y = 0;
   KDSize indexSize = indexLayout() != nullptr ? indexLayout()->size() : KDSize(k_leftRadixWidth,0);
-  if (child == indexLayout()) {
-    x = 0;
-    y = baseline() - indexSize.height() -  k_indexHeight;
-  } else if (child == radicandLayout()) {
+  if (child == radicandLayout()) {
     x = indexSize.width() + 2*k_widthMargin + k_radixLineThickness;
     y = baseline() - radicandLayout()->baseline();
+  } else if (indexLayout() && child == indexLayout()) {
+    x = 0;
+    y = baseline() - indexSize.height() -  k_indexHeight;
   } else {
     assert(false);
   }
@@ -277,7 +281,10 @@ ExpressionLayout * NthRootLayout::radicandLayout() {
 }
 
 ExpressionLayout * NthRootLayout::indexLayout() {
-  return editableChild(1);
+  if (numberOfChildren() > 1) {
+    return editableChild(1);
+  }
+  return nullptr;
 }
 
 }
diff --git a/poincare/src/layout/nth_root_layout.h b/poincare/src/layout/nth_root_layout.h
index c04f5c7f2..fb2a54048 100644
--- a/poincare/src/layout/nth_root_layout.h
+++ b/poincare/src/layout/nth_root_layout.h
@@ -1,16 +1,16 @@
 #ifndef POINCARE_NTH_ROOT_LAYOUT_H
 #define POINCARE_NTH_ROOT_LAYOUT_H
 
-#include <poincare/static_layout_hierarchy.h>
+#include <poincare/bounded_static_layout_hierarchy.h>
 #include <poincare/layout_engine.h>
 
 namespace Poincare {
 
-class NthRootLayout : public StaticLayoutHierarchy<2> {
+class NthRootLayout : public BoundedStaticLayoutHierarchy<2> {
 public:
   constexpr static KDCoordinate k_leftRadixHeight = 8;
   constexpr static KDCoordinate k_leftRadixWidth = 5;
-  using StaticLayoutHierarchy::StaticLayoutHierarchy;
+  using BoundedStaticLayoutHierarchy::BoundedStaticLayoutHierarchy;
   ExpressionLayout * clone() const override;
 
   /* Dynamic Layout*/
diff --git a/poincare/src/layout/static_layout_hierarchy.cpp b/poincare/src/layout/static_layout_hierarchy.cpp
index 76314772e..224902945 100644
--- a/poincare/src/layout/static_layout_hierarchy.cpp
+++ b/poincare/src/layout/static_layout_hierarchy.cpp
@@ -52,8 +52,7 @@ void StaticLayoutHierarchy<T>::build(const ExpressionLayout * const * operands,
   assert(operands != nullptr);
   assert(numberOfOperands <= T);
   for (int i=0; i < numberOfOperands; i++) {
-    assert(operands[i] != nullptr);
-    if (cloneOperands) {
+    if (cloneOperands && operands[i] != nullptr) {
       m_children[i] = operands[i]->clone();
     } else {
       m_children[i] = operands[i];