diff --git a/poincare/include/poincare/addition.h b/poincare/include/poincare/addition.h
index a8c3a490c..4caa285ec 100644
--- a/poincare/include/poincare/addition.h
+++ b/poincare/include/poincare/addition.h
@@ -39,7 +39,7 @@ public:
   }
 private:
   // Layout
-  bool childNeedsParenthesis(const SerializationHelperInterface * child) const override;
+  bool childNeedsParenthesis(const TreeNode * child) const override;
   Layout createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
   int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override {
     return SerializationHelper::Infix(this, buffer, bufferSize, floatDisplayMode, numberOfSignificantDigits, name());
diff --git a/poincare/include/poincare/division.h b/poincare/include/poincare/division.h
index bf3044a25..3ce1819f3 100644
--- a/poincare/include/poincare/division.h
+++ b/poincare/include/poincare/division.h
@@ -42,7 +42,7 @@ public:
   }
 
   // Layout
-  bool childNeedsParenthesis(const SerializationHelperInterface * child) const override;
+  bool childNeedsParenthesis(const TreeNode * child) const override;
   Layout createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
   int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override {
     return SerializationHelper::Infix(this, buffer, bufferSize, floatDisplayMode, numberOfSignificantDigits, "/");
diff --git a/poincare/include/poincare/expression_node.h b/poincare/include/poincare/expression_node.h
index 3b558a8b5..c8c90a223 100644
--- a/poincare/include/poincare/expression_node.h
+++ b/poincare/include/poincare/expression_node.h
@@ -4,7 +4,6 @@
 #include <poincare/tree_node.h>
 #include <poincare/evaluation.h>
 #include <poincare/layout.h>
-#include <poincare/serialization_helper_interface.h>
 #include <poincare/context.h>
 #include <stdint.h>
 
@@ -13,7 +12,7 @@ namespace Poincare {
 /* Methods preceded by '*!*' interfere with the expression pool, which can make
  * 'this' outdated. They should only be called in a wrapper on Expression. */
 
-class ExpressionNode : public TreeNode, public SerializationHelperInterface {
+class ExpressionNode : public TreeNode {
   friend class AdditionNode;
   friend class DivisionNode;
   friend class NAryExpressionNode;
@@ -159,10 +158,6 @@ protected:
   /* Hierarchy */
   ExpressionNode * parent() const override { return static_cast<ExpressionNode *>(TreeNode::parent()); }
   Direct<ExpressionNode> children() const { return Direct<ExpressionNode>(this); }
-
-  /* SerializationHelperInterface */
-  SerializationHelperInterface * serializableChildAtIndex(int i) const override { return childAtIndex(i); }
-  int numberOfSerializableChildren() const override { return numberOfChildren(); }
 };
 
 }
diff --git a/poincare/include/poincare/factorial.h b/poincare/include/poincare/factorial.h
index 6affcfd0e..0c58aaeea 100644
--- a/poincare/include/poincare/factorial.h
+++ b/poincare/include/poincare/factorial.h
@@ -23,7 +23,7 @@ public:
   Type type() const override { return Type::Factorial; }
 private:
   // Layout
-  bool childNeedsParenthesis(const SerializationHelperInterface * child) const override;
+  bool childNeedsParenthesis(const TreeNode * child) const override;
   Layout createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
   int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
   // Simplication
diff --git a/poincare/include/poincare/fraction_layout.h b/poincare/include/poincare/fraction_layout.h
index a0712bf67..5d856b0ce 100644
--- a/poincare/include/poincare/fraction_layout.h
+++ b/poincare/include/poincare/fraction_layout.h
@@ -43,7 +43,7 @@ public:
 
 protected:
   // SerializationInterface
-  bool childNeedsParenthesis(const SerializationHelperInterface * child) const override { return true; }
+  bool childNeedsParenthesis(const TreeNode * child) const override { return true; }
   // LayoutNode
   KDSize computeSize() override;
   KDCoordinate computeBaseline() override;
diff --git a/poincare/include/poincare/layout_node.h b/poincare/include/poincare/layout_node.h
index 5abdb2057..c474c1c59 100644
--- a/poincare/include/poincare/layout_node.h
+++ b/poincare/include/poincare/layout_node.h
@@ -2,7 +2,6 @@
 #define POINCARE_LAYOUT_NODE_H
 
 #include <poincare/tree_node.h>
-#include <poincare/serialization_helper_interface.h>
 #include <kandinsky.h>
 #include <ion/charset.h>
 
@@ -11,7 +10,7 @@ namespace Poincare {
 class LayoutCursor;
 class Layout;
 
-class LayoutNode : public TreeNode, public SerializationHelperInterface {
+class LayoutNode : public TreeNode {
   friend class Layout;
 public:
   enum class VerticalDirection {
@@ -39,10 +38,6 @@ public:
   //TODO: invalid cache when tempering with hierarchy
   virtual void invalidAllSizesPositionsAndBaselines();
 
-  // SerializationHelperInterface
-  SerializationHelperInterface * serializableChildAtIndex(int i) const override { return childAtIndex(i); }
-  int numberOfSerializableChildren() const override { return numberOfChildren(); }
-
   // Tree
   LayoutNode * parent() const override { return static_cast<LayoutNode *>(TreeNode::parent()); }
   LayoutNode * childAtIndex(int i) const override { return static_cast<LayoutNode *>(TreeNode::childAtIndex(i)); }
diff --git a/poincare/include/poincare/multiplication.h b/poincare/include/poincare/multiplication.h
index 5c3df8a48..70641d674 100644
--- a/poincare/include/poincare/multiplication.h
+++ b/poincare/include/poincare/multiplication.h
@@ -37,7 +37,7 @@ private:
   Expression setSign(Sign s, Context & context, Preferences::AngleUnit angleUnit) override;
 
   // Layout
-  bool childNeedsParenthesis(const SerializationHelperInterface * child) const override;
+  bool childNeedsParenthesis(const TreeNode * child) const override;
   Layout createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
 
   // Serialize
diff --git a/poincare/include/poincare/opposite.h b/poincare/include/poincare/opposite.h
index 505856ebc..45c2e4b33 100644
--- a/poincare/include/poincare/opposite.h
+++ b/poincare/include/poincare/opposite.h
@@ -36,7 +36,7 @@ public:
   }
 
   // Layout
-  bool childNeedsParenthesis(const SerializationHelperInterface * child) const override;
+  bool childNeedsParenthesis(const TreeNode * child) const override;
   Layout createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
   int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode = Preferences::PrintFloatMode::Decimal, int numberOfSignificantDigits = 0) const override;
 
diff --git a/poincare/include/poincare/power.h b/poincare/include/poincare/power.h
index c139fde92..1ec939210 100644
--- a/poincare/include/poincare/power.h
+++ b/poincare/include/poincare/power.h
@@ -39,7 +39,7 @@ private:
   Layout createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
 
   // Serialize
-  bool childNeedsParenthesis(const SerializationHelperInterface * child) const override;
+  bool childNeedsParenthesis(const TreeNode * child) const override;
   int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override {
     return SerializationHelper::Infix(this, buffer, bufferSize, floatDisplayMode, numberOfSignificantDigits, name());
   }
diff --git a/poincare/include/poincare/serialization_helper.h b/poincare/include/poincare/serialization_helper.h
index b31cc450a..2135d0aea 100644
--- a/poincare/include/poincare/serialization_helper.h
+++ b/poincare/include/poincare/serialization_helper.h
@@ -1,14 +1,14 @@
 #ifndef POINCARE_SERIALIZATION_HELPER_H
 #define POINCARE_SERIALIZATION_HELPER_H
 
-#include <poincare/serialization_helper_interface.h>
+#include <poincare/tree_node.h>
 
 namespace Poincare {
 
 namespace SerializationHelper {
   /* SerializableReference to Text */
   int Infix(
-      const SerializationHelperInterface * interface,
+      const TreeNode * node,
       char * buffer,
       int bufferSize,
       Preferences::PrintFloatMode floatDisplayMode,
@@ -18,7 +18,7 @@ namespace SerializationHelper {
       int lastChildIndex = -1);
 
   int Prefix(
-      const SerializationHelperInterface * interface,
+      const TreeNode * node,
       char * buffer,
       int bufferSize,
       Preferences::PrintFloatMode floatDisplayMode,
diff --git a/poincare/include/poincare/serialization_helper_interface.h b/poincare/include/poincare/serialization_helper_interface.h
deleted file mode 100644
index 5ed9fad73..000000000
--- a/poincare/include/poincare/serialization_helper_interface.h
+++ /dev/null
@@ -1,19 +0,0 @@
-#ifndef POINCARE_SERIALIZATION_HELPER_INTERFACE_H
-#define POINCARE_SERIALIZATION_HELPER_INTERFACE_H
-
-#include <poincare/preferences.h>
-
-namespace Poincare {
-
-class SerializationHelperInterface {
-public:
-  virtual int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode = Preferences::PrintFloatMode::Decimal, int numberOfSignificantDigits = 0) const = 0;
-  virtual bool childNeedsParenthesis(const SerializationHelperInterface * child) const { return false; };
-
-  virtual SerializationHelperInterface * serializableChildAtIndex(int i) const = 0;
-  virtual int numberOfSerializableChildren() const = 0;
-};
-
-}
-
-#endif
diff --git a/poincare/include/poincare/subtraction.h b/poincare/include/poincare/subtraction.h
index a46734214..44fdfa52b 100644
--- a/poincare/include/poincare/subtraction.h
+++ b/poincare/include/poincare/subtraction.h
@@ -35,7 +35,7 @@ public:
   }
 
   /* Layout */
-  bool childNeedsParenthesis(const SerializationHelperInterface * child) const override;
+  bool childNeedsParenthesis(const TreeNode * child) const override;
   Layout createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
   int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
 
diff --git a/poincare/include/poincare/tree_node.h b/poincare/include/poincare/tree_node.h
index c4d4a51ee..f915a998e 100644
--- a/poincare/include/poincare/tree_node.h
+++ b/poincare/include/poincare/tree_node.h
@@ -8,6 +8,7 @@
 #if POINCARE_TREE_LOG
 #include <ostream>
 #endif
+#include <poincare/preferences.h>
 
 /* What's in a TreeNode, really?
  *  - a vtable pointer
@@ -62,6 +63,10 @@ public:
   // AddChild collateral effect
   virtual void didAddChildAtIndex(int newNumberOfChildren) {}
 
+  // Serialization
+  virtual int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode = Preferences::PrintFloatMode::Decimal, int numberOfSignificantDigits = 0) const { assert(false); return 0; }
+  virtual bool childNeedsParenthesis(const TreeNode * child) const { return false; };
+
   template <typename T>
   class Iterator {
   public:
diff --git a/poincare/src/addition.cpp b/poincare/src/addition.cpp
index bcfd12efa..a09374e41 100644
--- a/poincare/src/addition.cpp
+++ b/poincare/src/addition.cpp
@@ -28,7 +28,7 @@ int AdditionNode::getPolynomialCoefficients(char symbolName, Expression coeffici
 // Private
 
 // Layout
-bool AdditionNode::childNeedsParenthesis(const SerializationHelperInterface * child) const {
+bool AdditionNode::childNeedsParenthesis(const TreeNode * child) const {
   if ((static_cast<const ExpressionNode *>(child)->isNumber() && static_cast<const ExpressionNode *>(child)->sign() == Sign::Negative) || static_cast<const ExpressionNode *>(child)->type() == Type::Opposite) {
     return true;
   }
diff --git a/poincare/src/division.cpp b/poincare/src/division.cpp
index c904e2f1d..ac6cd7365 100644
--- a/poincare/src/division.cpp
+++ b/poincare/src/division.cpp
@@ -18,7 +18,7 @@ int DivisionNode::polynomialDegree(char symbolName) const {
   return childAtIndex(0)->polynomialDegree(symbolName);
 }
 
-bool DivisionNode::childNeedsParenthesis(const SerializationHelperInterface * child) const {
+bool DivisionNode::childNeedsParenthesis(const TreeNode * child) const {
   if (static_cast<const ExpressionNode *>(child)->isNumber() && static_cast<const ExpressionNode *>(child)->sign() == Sign::Negative) {
     return true;
   }
diff --git a/poincare/src/factorial.cpp b/poincare/src/factorial.cpp
index 61a4d3620..f08c192f6 100644
--- a/poincare/src/factorial.cpp
+++ b/poincare/src/factorial.cpp
@@ -13,7 +13,7 @@ namespace Poincare {
 
 // Layout
 
-bool FactorialNode::childNeedsParenthesis(const SerializationHelperInterface * child) const {
+bool FactorialNode::childNeedsParenthesis(const TreeNode * child) const {
   if (static_cast<const ExpressionNode *>(child)->isNumber() && static_cast<const ExpressionNode *>(child)->sign() == Sign::Negative) {
     return true;
   }
diff --git a/poincare/src/multiplication.cpp b/poincare/src/multiplication.cpp
index 91ae1b13d..9dcfba203 100644
--- a/poincare/src/multiplication.cpp
+++ b/poincare/src/multiplication.cpp
@@ -67,7 +67,7 @@ Expression MultiplicationNode::setSign(Sign s, Context & context, Preferences::A
   return Multiplication(this).setSign(s, context, angleUnit);
 }
 
-bool MultiplicationNode::childNeedsParenthesis(const SerializationHelperInterface * child) const {
+bool MultiplicationNode::childNeedsParenthesis(const TreeNode * child) const {
   if (static_cast<const ExpressionNode *>(child)->isNumber() && static_cast<const ExpressionNode *>(child)->sign() == Sign::Negative) {
     return true;
   }
diff --git a/poincare/src/opposite.cpp b/poincare/src/opposite.cpp
index cefe5abe2..39cc12cfa 100644
--- a/poincare/src/opposite.cpp
+++ b/poincare/src/opposite.cpp
@@ -29,7 +29,7 @@ ExpressionNode::Sign OppositeNode::sign() const {
 
 /* Layout */
 
-bool OppositeNode::childNeedsParenthesis(const SerializationHelperInterface * child) const {
+bool OppositeNode::childNeedsParenthesis(const TreeNode * child) const {
   if (static_cast<const ExpressionNode *>(child)->isNumber() && static_cast<const ExpressionNode *>(child)->sign() == Sign::Negative) {
     return true;
   }
diff --git a/poincare/src/power.cpp b/poincare/src/power.cpp
index f783a6520..8e6052257 100644
--- a/poincare/src/power.cpp
+++ b/poincare/src/power.cpp
@@ -111,7 +111,7 @@ Layout PowerNode::createLayout(Preferences::PrintFloatMode floatDisplayMode, int
 
 // Serialize
 
-bool PowerNode::childNeedsParenthesis(const SerializationHelperInterface * child) const {
+bool PowerNode::childNeedsParenthesis(const TreeNode * child) const {
   if (static_cast<const ExpressionNode *>(child)->isNumber() && static_cast<const ExpressionNode *>(child)->sign() == Sign::Negative) {
     return true;
   }
diff --git a/poincare/src/serialization_helper.cpp b/poincare/src/serialization_helper.cpp
index 954c294a9..3375d3b6f 100644
--- a/poincare/src/serialization_helper.cpp
+++ b/poincare/src/serialization_helper.cpp
@@ -4,9 +4,9 @@
 
 namespace Poincare {
 
-static void serializeChild(const SerializationHelperInterface * childInterface, const SerializationHelperInterface * interface, char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfDigits, int * numberOfChar) {
+static void serializeChild(const TreeNode * childNode, const TreeNode * parentNode, char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfDigits, int * numberOfChar) {
   // Write the child with parentheses if needed
-  bool addParentheses = interface->childNeedsParenthesis(childInterface);
+  bool addParentheses = parentNode->childNeedsParenthesis(childNode);
   if (addParentheses) {
     buffer[*numberOfChar] = '(';
     *numberOfChar = *numberOfChar + 1;
@@ -14,7 +14,7 @@ static void serializeChild(const SerializationHelperInterface * childInterface,
       return;
     }
   }
-  *numberOfChar += childInterface->serialize(buffer + *numberOfChar, bufferSize - *numberOfChar, floatDisplayMode, numberOfDigits);
+  *numberOfChar += childNode->serialize(buffer + *numberOfChar, bufferSize - *numberOfChar, floatDisplayMode, numberOfDigits);
   if (*numberOfChar >= bufferSize-1) {
     return;
   }
@@ -25,7 +25,7 @@ static void serializeChild(const SerializationHelperInterface * childInterface,
 }
 
 int SerializationHelper::Infix(
-    const SerializationHelperInterface * interface,
+    const TreeNode * node,
     char * buffer,
     int bufferSize,
     Preferences::PrintFloatMode floatDisplayMode,
@@ -44,13 +44,13 @@ int SerializationHelper::Infix(
     return 0;
   }
 
-  // Get some information on the interface
+  // Get some information on the node
   int numberOfChar = 0;
-  int numberOfChildren = interface->numberOfSerializableChildren();
+  int numberOfChildren = node->numberOfChildren();
   assert(numberOfChildren > 0);
 
   // Write the first child, with parentheses if needed
-  serializeChild(interface->serializableChildAtIndex(firstChildIndex), interface, buffer, bufferSize, floatDisplayMode, numberOfDigits, &numberOfChar);
+  serializeChild(node->childAtIndex(firstChildIndex), node, buffer, bufferSize, floatDisplayMode, numberOfDigits, &numberOfChar);
   if (numberOfChar >= bufferSize-1) {
     return bufferSize-1;
   }
@@ -63,7 +63,7 @@ int SerializationHelper::Infix(
       return bufferSize-1;
     }
     // Write the child, with parentheses if needed
-    serializeChild(interface->serializableChildAtIndex(i), interface, buffer, bufferSize, floatDisplayMode, numberOfDigits, &numberOfChar);
+    serializeChild(node->childAtIndex(i), node, buffer, bufferSize, floatDisplayMode, numberOfDigits, &numberOfChar);
     if (numberOfChar >= bufferSize-1) {
       return bufferSize-1;
     }
@@ -75,7 +75,7 @@ int SerializationHelper::Infix(
 }
 
 int SerializationHelper::Prefix(
-    const SerializationHelperInterface * interface,
+    const TreeNode * node,
     char * buffer,
     int bufferSize,
     Preferences::PrintFloatMode floatDisplayMode,
@@ -104,7 +104,7 @@ int SerializationHelper::Prefix(
     return bufferSize-1;
   }
 
-  int childrenCount = interface->numberOfSerializableChildren();
+  int childrenCount = node->numberOfChildren();
   if (childrenCount > 0) {
     if (!writeFirstChild) {
       assert(childrenCount > 1);
@@ -112,7 +112,7 @@ int SerializationHelper::Prefix(
     int firstChildIndex = writeFirstChild ? 0 : 1;
 
     // Write the first child
-    numberOfChar += interface->serializableChildAtIndex(firstChildIndex)->serialize(buffer+numberOfChar, bufferSize-numberOfChar, floatDisplayMode, numberOfDigits);
+    numberOfChar += node->childAtIndex(firstChildIndex)->serialize(buffer+numberOfChar, bufferSize-numberOfChar, floatDisplayMode, numberOfDigits);
     if (numberOfChar >= bufferSize-1) {
       return bufferSize-1;
     }
@@ -123,7 +123,7 @@ int SerializationHelper::Prefix(
       if (numberOfChar >= bufferSize-1) {
         return bufferSize-1;
       }
-      numberOfChar += interface->serializableChildAtIndex(i)->serialize(buffer+numberOfChar, bufferSize-numberOfChar, floatDisplayMode, numberOfDigits);
+      numberOfChar += node->childAtIndex(i)->serialize(buffer+numberOfChar, bufferSize-numberOfChar, floatDisplayMode, numberOfDigits);
       if (numberOfChar >= bufferSize-1) {
         return bufferSize-1;
       }
diff --git a/poincare/src/subtraction.cpp b/poincare/src/subtraction.cpp
index 4d1d3535a..5a12cac31 100644
--- a/poincare/src/subtraction.cpp
+++ b/poincare/src/subtraction.cpp
@@ -22,7 +22,7 @@ int SubtractionNode::polynomialDegree(char symbolName) const {
 
 // Private
 
-bool SubtractionNode::childNeedsParenthesis(const SerializationHelperInterface * child) const {
+bool SubtractionNode::childNeedsParenthesis(const TreeNode * child) const {
   if (static_cast<const ExpressionNode *>(child)->isNumber() && static_cast<const ExpressionNode *>(child)->sign() == Sign::Negative) {
     return true;
   }