diff --git a/CMakeLists.txt b/CMakeLists.txt
index d2ad461..67a3bd8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -46,8 +46,6 @@ add_library(dom STATIC
   src/ftxui/dom/blink.cpp
   src/ftxui/dom/bold.cpp
   src/ftxui/dom/border.cpp
-  src/ftxui/dom/box_helper.cpp
-  src/ftxui/dom/box_helper.hpp
   src/ftxui/dom/clear_under.cpp
   src/ftxui/dom/color.cpp
   src/ftxui/dom/composite_decorator.cpp
diff --git a/src/ftxui/dom/box_helper.cpp b/src/ftxui/dom/box_helper.cpp
deleted file mode 100644
index d90da2a..0000000
--- a/src/ftxui/dom/box_helper.cpp
+++ /dev/null
@@ -1,85 +0,0 @@
-#include "ftxui/dom/box_helper.hpp"
-
-namespace ftxui {
-namespace box_helper {
-
-namespace {
-// Called when the size allowed is greater than the requested size. This
-// distributes the extra spaces toward the flexible elements, in relative
-// proportions.
-void ComputeGrow(std::vector<Element>* elements,
-                 int extra_space,
-                 int flex_grow_sum) {
-  for (Element& element : *elements) {
-    int added_space =
-        extra_space * element.flex_grow / std::max(flex_grow_sum, 1);
-    extra_space -= added_space;
-    flex_grow_sum -= element.flex_grow;
-    element.size = element.min_size + added_space;
-  }
-}
-
-// Called when the size allowed is lower than the requested size, and the
-// shrinkable element can absorbe the (negative) extra_space. This distribute
-// the extra_space toward those.
-void ComputeShrinkEasy(std::vector<Element>* elements,
-                       int extra_space,
-                       int flex_shrink_sum) {
-  for (Element& element : *elements) {
-    int added_space = extra_space * element.min_size * element.flex_shrink /
-                      std::max(flex_shrink_sum, 1);
-    extra_space -= added_space;
-    flex_shrink_sum -= element.flex_shrink * element.min_size;
-    element.size = element.min_size + added_space;
-  }
-}
-
-// Called when the size allowed is lower than the requested size, and the
-// shrinkable element can not absorbe the (negative) extra_space. This assign
-// zero to shrinkable elements and distribute the remaining (negative)
-// extra_space toward the other non shrinkable elements.
-void ComputeShrinkHard(std::vector<Element>* elements,
-                       int extra_space,
-                       int size) {
-  for (Element& element : *elements) {
-    if (element.flex_shrink) {
-      element.size = 0;
-      continue;
-    }
-
-    int added_space = extra_space * element.min_size / std::max(1, size);
-    extra_space -= added_space;
-    size -= element.min_size;
-
-    element.size = element.min_size + added_space;
-  }
-}
-
-}  // namespace
-
-void Compute(std::vector<Element>* elements, int target_size) {
-  int size = 0;
-  int flex_grow_sum = 0;
-  int flex_shrink_sum = 0;
-  int flex_shrink_size = 0;
-
-  for (auto& element : *elements) {
-    flex_grow_sum += element.flex_grow;
-    flex_shrink_sum += element.min_size * element.flex_shrink;
-    if (element.flex_shrink)
-      flex_shrink_size += element.min_size;
-    size += element.min_size;
-  }
-
-  int extra_space = target_size - size;
-  if (extra_space >= 0)
-    ComputeGrow(elements, extra_space, flex_grow_sum);
-  else if (flex_shrink_size + extra_space >= 0)
-    ComputeShrinkEasy(elements, extra_space, flex_shrink_sum);
-  else
-    ComputeShrinkHard(elements, extra_space + flex_shrink_size,
-                      size - flex_shrink_size);
-}
-
-}  // namespace box_helper
-}  // namespace ftxui
diff --git a/src/ftxui/dom/box_helper.hpp b/src/ftxui/dom/box_helper.hpp
deleted file mode 100644
index 9e0ebda..0000000
--- a/src/ftxui/dom/box_helper.hpp
+++ /dev/null
@@ -1,24 +0,0 @@
-#ifndef FTXUI_DOM_BOX_HELPER_HPP
-#define FTXUI_DOM_BOX_HELPER_HPP
-
-#include <vector>
-
-namespace ftxui {
-namespace box_helper {
-
-struct Element {
-  // Input:
-  int min_size = 0;
-  int flex_grow = 0;
-  int flex_shrink = 0;
-
-  // Output;
-  int size = 0;
-};
-
-void Compute(std::vector<Element>* elements, int target_size);
-
-}  // namespace box_helper
-}  // namespace ftxui
-
-#endif /* end of include guard: FTXUI_DOM_BOX_HELPER_HPP */
diff --git a/src/ftxui/dom/hbox.cpp b/src/ftxui/dom/hbox.cpp
index 55bc115..092e38f 100644
--- a/src/ftxui/dom/hbox.cpp
+++ b/src/ftxui/dom/hbox.cpp
@@ -3,7 +3,6 @@
 #include <utility>    // for move
 #include <vector>     // for vector
 
-#include "ftxui/dom/box_helper.hpp"   // for Box
 #include "ftxui/dom/elements.hpp"     // for Element, Elements, hbox
 #include "ftxui/dom/node.hpp"         // for Node
 #include "ftxui/dom/requirement.hpp"  // for Requirement
@@ -39,23 +38,92 @@ class HBox : public Node {
   void SetBox(Box box) override {
     Node::SetBox(box);
 
-    std::vector<box_helper::Element> elements(children_.size());
-    for (size_t i = 0; i < children_.size(); ++i) {
-      auto& element = elements[i];
-      const auto& requirement = children_[i]->requirement();
-      element.min_size = requirement.min_x;
-      element.flex_grow = requirement.flex_grow_x;
-      element.flex_shrink = requirement.flex_shrink_x;
-    }
-    int target_size = box.x_max - box.x_min + 1;
-    box_helper::Compute(&elements, target_size);
+    int space = box.x_max - box.x_min + 1;
+    int extra_space = space - requirement_.min_x;
 
+    int size = 0;
+    int flex_grow_sum = 0;
+    int flex_shrink_sum = 0;
+    int flex_shrink_size = 0;
+    for (auto& child : children_) {
+      const Requirement& r = child->requirement();
+      flex_grow_sum += r.flex_grow_x;
+      flex_shrink_sum += r.min_x * r.flex_shrink_x;
+      if (r.flex_shrink_x) {
+        flex_shrink_size += r.min_x;
+      }
+      size += r.min_x;
+    }
+
+    if (extra_space >= 0)
+      SetBoxGrow(box, extra_space, flex_grow_sum);
+    else if (flex_shrink_size + extra_space >= 0)
+      SetBoxShrinkEasy(box, extra_space, flex_shrink_sum);
+    else
+      SetBoxShrinkHard(box, extra_space + flex_shrink_size,
+                       size - flex_shrink_size);
+  }
+
+  void SetBoxGrow(Box box, int extra_space, int flex_grow_sum) {
     int x = box.x_min;
-    for (size_t i = 0; i < children_.size(); ++i) {
-      box.x_min = x;
-      box.x_max = x + elements[i].size - 1;
-      children_[i]->SetBox(box);
-      x = box.x_max + 1;
+    for (auto& child : children_) {
+      Box child_box = box;
+      const Requirement& r = child->requirement();
+
+      int added_space =
+          extra_space * r.flex_grow_x / std::max(flex_grow_sum, 1);
+      extra_space -= added_space;
+      flex_grow_sum -= r.flex_grow_x;
+
+      child_box.x_min = x;
+      child_box.x_max = x + r.min_x + added_space - 1;
+
+      child->SetBox(child_box);
+      x = child_box.x_max + 1;
+    }
+  }
+
+  void SetBoxShrinkEasy(Box box, int extra_space, int flex_shrink_sum) {
+    int x = box.x_min;
+    for (auto& child : children_) {
+      Box child_box = box;
+      const Requirement& r = child->requirement();
+
+      int added_space = extra_space * r.min_x * r.flex_shrink_x /
+                        std::max(flex_shrink_sum, 1);
+      extra_space -= added_space;
+      flex_shrink_sum -= r.flex_shrink_x * r.min_x;
+
+      child_box.x_min = x;
+      child_box.x_max = x + r.min_x + added_space - 1;
+
+      child->SetBox(child_box);
+      x = child_box.x_max + 1;
+    }
+  }
+
+  void SetBoxShrinkHard(Box box, int extra_space, int size) {
+    int x = box.x_min;
+    for (auto& child : children_) {
+      Box child_box = box;
+      const Requirement& r = child->requirement();
+
+      if (r.flex_shrink_x) {
+        child_box.x_min = x;
+        child_box.x_max = x - 1;
+        child->SetBox(child_box);
+        continue;
+      }
+
+      int added_space = extra_space * r.min_x / std::max(1, size);
+      extra_space -= added_space;
+      size -= r.min_x;
+
+      child_box.x_min = x;
+      child_box.x_max = x + r.min_x + added_space - 1;
+
+      child->SetBox(child_box);
+      x = child_box.x_max + 1;
     }
   }
 };
diff --git a/src/ftxui/dom/vbox.cpp b/src/ftxui/dom/vbox.cpp
index 6dd26e7..1ed02d8 100644
--- a/src/ftxui/dom/vbox.cpp
+++ b/src/ftxui/dom/vbox.cpp
@@ -3,7 +3,6 @@
 #include <utility>    // for move
 #include <vector>     // for vector
 
-#include "ftxui/dom/box_helper.hpp"  // for Box
 #include "ftxui/dom/elements.hpp"     // for Element, Elements, vbox
 #include "ftxui/dom/node.hpp"         // for Node
 #include "ftxui/dom/requirement.hpp"  // for Requirement
@@ -39,23 +38,92 @@ class VBox : public Node {
   void SetBox(Box box) override {
     Node::SetBox(box);
 
-    std::vector<box_helper::Element> elements(children_.size());
-    for (size_t i = 0; i < children_.size(); ++i) {
-      auto& element = elements[i];
-      const auto& requirement = children_[i]->requirement();
-      element.min_size = requirement.min_y;
-      element.flex_grow = requirement.flex_grow_y;
-      element.flex_shrink = requirement.flex_shrink_y;
-    }
-    int target_size = box.y_max - box.y_min + 1;
-    box_helper::Compute(&elements, target_size);
+    int space = box.y_max - box.y_min + 1;
+    int extra_space = space - requirement_.min_y;
 
-    int x = box.x_min;
-    for (size_t i = 0; i < children_.size(); ++i) {
-      box.y_min = x;
-      box.y_max = x + elements[i].size - 1;
-      children_[i]->SetBox(box);
-      x = box.y_max + 1;
+    int size = 0;
+    int flex_grow_sum = 0;
+    int flex_shrink_sum = 0;
+    int flex_shrink_size = 0;
+    for (auto& child : children_) {
+      const Requirement& r = child->requirement();
+      flex_grow_sum += r.flex_grow_y;
+      flex_shrink_sum += r.min_y * r.flex_shrink_y;
+      if (r.flex_shrink_y) {
+        flex_shrink_size += r.min_y;
+      }
+      size += r.min_y;
+    }
+
+    if (extra_space >= 0)
+      SetBoxGrow(box, extra_space, flex_grow_sum);
+    else if (flex_shrink_size + extra_space >= 0)
+      SetBoxShrinkEasy(box, extra_space, flex_shrink_sum);
+    else
+      SetBoxShrinkHard(box, extra_space + flex_shrink_size,
+                       size - flex_shrink_size);
+  }
+
+  void SetBoxGrow(Box box, int extra_space, int flex_grow_sum) {
+    int y = box.y_min;
+    for (auto& child : children_) {
+      Box child_box = box;
+      const Requirement& r = child->requirement();
+
+      int added_space =
+          extra_space * r.flex_grow_y / std::max(flex_grow_sum, 1);
+      extra_space -= added_space;
+      flex_grow_sum -= r.flex_grow_y;
+
+      child_box.y_min = y;
+      child_box.y_max = y + r.min_y + added_space - 1;
+
+      child->SetBox(child_box);
+      y = child_box.y_max + 1;
+    }
+  }
+
+  void SetBoxShrinkEasy(Box box, int extra_space, int flex_shrink_sum) {
+    int y = box.y_min;
+    for (auto& child : children_) {
+      Box child_box = box;
+      const Requirement& r = child->requirement();
+
+      int added_space = extra_space * r.min_y * r.flex_shrink_y /
+                        std::max(flex_shrink_sum, 1);
+      extra_space -= added_space;
+      flex_shrink_sum -= r.flex_shrink_y * r.min_y;
+
+      child_box.y_min = y;
+      child_box.y_max = y + r.min_y + added_space - 1;
+
+      child->SetBox(child_box);
+      y = child_box.y_max + 1;
+    }
+  }
+
+  void SetBoxShrinkHard(Box box, int extra_space, int size) {
+    int y = box.y_min;
+    for (auto& child : children_) {
+      Box child_box = box;
+      const Requirement& r = child->requirement();
+
+      if (r.flex_shrink_y) {
+        child_box.y_min = y;
+        child_box.y_max = y - 1;
+        child->SetBox(child_box);
+        continue;
+      }
+
+      int added_space = extra_space * r.min_y / std::max(1, size);
+      extra_space -= added_space;
+      size -= r.min_y;
+
+      child_box.y_min = y;
+      child_box.y_max = y + r.min_y + added_space - 1;
+
+      child->SetBox(child_box);
+      y = child_box.y_max + 1;
     }
   }
 };