diff --git a/poincare/src/layout.cpp b/poincare/src/layout.cpp
index 1caa20ce6..bc81e3ec1 100644
--- a/poincare/src/layout.cpp
+++ b/poincare/src/layout.cpp
@@ -176,7 +176,13 @@ void Layout::addSibling(LayoutCursor * cursor, Layout sibling, bool moveCursor)
   assert(!p.isUninitialized());
   if (p.type() == LayoutNode::Type::HorizontalLayout) {
     int indexInParent = p.indexOfChild(*this);
-    int siblingIndex = cursor->position() == LayoutCursor::Position::Left ? indexInParent : indexInParent + 1;
+    int indexOfCursor = p.indexOfChild(cursor->layout());
+    /* indexOfCursor == -1 if cursor->layout() is not a child of p. This should
+     * never happen, as addSibling is only called from inside
+     * LayoutField::handleEventWithText, and LayoutField is supposed to keep
+     * its cursor up to date.*/
+    assert(indexOfCursor >= 0);
+    int siblingIndex = cursor->position() == LayoutCursor::Position::Left ? indexOfCursor : indexOfCursor + 1;
 
     /* Special case: If the neighbour sibling is a VerticalOffsetLayout, let it
      * handle the insertion of the new sibling. Do not enter the special case if
diff --git a/poincare/src/vertical_offset_layout.cpp b/poincare/src/vertical_offset_layout.cpp
index 40d6571ff..1ab101e27 100644
--- a/poincare/src/vertical_offset_layout.cpp
+++ b/poincare/src/vertical_offset_layout.cpp
@@ -236,7 +236,7 @@ bool VerticalOffsetLayoutNode::willAddSibling(LayoutCursor * cursor, LayoutNode
       // Add the Right parenthesis
       RightParenthesisLayout rightParenthesis = RightParenthesisLayout::Builder();
       if (cursor->position() == LayoutCursor::Position::Right) {
-         parentRef.addChildAtIndex(rightParenthesis, idxInParent + 1, parentRef.numberOfChildren(), nullptr);
+        parentRef.addChildAtIndex(rightParenthesis, idxInParent + 1, parentRef.numberOfChildren(), nullptr);
       } else {
         assert(cursor->position() == LayoutCursor::Position::Left);
         parentRef.addChildAtIndex(rightParenthesis, idxInParent, parentRef.numberOfChildren(), nullptr);