diff --git a/poincare/include/poincare/tree_node.h b/poincare/include/poincare/tree_node.h
index 36290867b..667e7a722 100644
--- a/poincare/include/poincare/tree_node.h
+++ b/poincare/include/poincare/tree_node.h
@@ -82,6 +82,7 @@ public:
   virtual void didAddChildAtIndex(int newNumberOfChildren) {}
 
   // Serialization
+  // Return the number of chars written, without the null-terminating char.
   virtual int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const { assert(false); return 0; }
   /* When serializing, we turn a tree into a string. In order not to lose
    * structure information, we sometimes need to add system parentheses (that
diff --git a/poincare/src/constant.cpp b/poincare/src/constant.cpp
index 9d13524cd..a02d89df1 100644
--- a/poincare/src/constant.cpp
+++ b/poincare/src/constant.cpp
@@ -14,6 +14,8 @@
 
 namespace Poincare {
 
+static inline int minInt(int x, int y) { return x < y ? x : y; }
+
 ConstantNode::ConstantNode(const char * newName, int length) : SymbolAbstractNode() {
   strlcpy(const_cast<char*>(name()), newName, length+1);
 }
@@ -66,7 +68,7 @@ int ConstantNode::serialize(char * buffer, int bufferSize, Preferences::PrintFlo
   if (bufferSize == 0) {
     return -1;
   }
-  return strlcpy(buffer, m_name, bufferSize);
+  return minInt(strlcpy(buffer, m_name, bufferSize), bufferSize - 1);
 }
 
 template<typename T>
diff --git a/poincare/src/decimal.cpp b/poincare/src/decimal.cpp
index bbc38eef8..2ffd0f477 100644
--- a/poincare/src/decimal.cpp
+++ b/poincare/src/decimal.cpp
@@ -109,11 +109,11 @@ int DecimalNode::convertToText(char * buffer, int bufferSize, Preferences::Print
     return -1;
   }
   buffer[bufferSize-1] = 0;
-  int currentChar = 0;
-  if (currentChar >= bufferSize-1) { return bufferSize-1; }
+  if (bufferSize == 1) {
+    return 0;
+  }
   if (unsignedMantissa().isZero()) {
-    currentChar += SerializationHelper::CodePoint(buffer + currentChar, bufferSize - currentChar, '0'); // This already writes the null terminating char
-    return currentChar;
+    return SerializationHelper::CodePoint(buffer, bufferSize, '0'); // This already writes the null terminating char
   }
   int exponent = m_exponent;
   char tempBuffer[PrintFloat::k_numberOfStoredSignificantDigits+1];
@@ -135,6 +135,7 @@ int DecimalNode::convertToText(char * buffer, int bufferSize, Preferences::Print
      * to 2000. To avoid printing 2.000, we removeZeroAtTheEnd here. */
     removeZeroAtTheEnd(&m);
   }
+  int currentChar = 0;
   if (m_negative) {
     currentChar += SerializationHelper::CodePoint(buffer + currentChar, bufferSize - currentChar, '-');
     if (currentChar >= bufferSize-1) { return bufferSize-1; }
diff --git a/poincare/src/factorial.cpp b/poincare/src/factorial.cpp
index 38afca245..7d2cafddc 100644
--- a/poincare/src/factorial.cpp
+++ b/poincare/src/factorial.cpp
@@ -77,8 +77,7 @@ int FactorialNode::serialize(char * buffer, int bufferSize, Preferences::PrintFl
   if ((numberOfChar < 0) || (numberOfChar >= bufferSize-1)) {
     return numberOfChar;
   }
-  numberOfChar += SerializationHelper::CodePoint(&buffer[numberOfChar], bufferSize-numberOfChar, '!');
-  buffer[numberOfChar] = 0;
+  numberOfChar += SerializationHelper::CodePoint(buffer+numberOfChar, bufferSize-numberOfChar, '!');
   return numberOfChar;
 }
 
diff --git a/poincare/src/fraction_layout.cpp b/poincare/src/fraction_layout.cpp
index da365de34..ab9bb044d 100644
--- a/poincare/src/fraction_layout.cpp
+++ b/poincare/src/fraction_layout.cpp
@@ -123,8 +123,7 @@ int FractionLayoutNode::serialize(char * buffer, int bufferSize, Preferences::Pr
     return -1;
   }
   buffer[bufferSize-1] = 0;
-  int numberOfChar = 0;
-  if (numberOfChar >= bufferSize-1) { return bufferSize-1;}
+  if (bufferSize == 1) { return 0;}
 
   /* Add System parenthesis to detect omitted multiplication:
    *   2
@@ -133,8 +132,8 @@ int FractionLayoutNode::serialize(char * buffer, int bufferSize, Preferences::Pr
    */
 
   // Add system parenthesis
-  numberOfChar+= SerializationHelper::CodePoint(buffer + numberOfChar, bufferSize - numberOfChar, UCodePointLeftSystemParenthesis);
-  if (numberOfChar >= bufferSize-1) { return bufferSize-1;}
+  int numberOfChar = SerializationHelper::CodePoint(buffer, bufferSize, UCodePointLeftSystemParenthesis);
+  if (numberOfChar >= bufferSize-1) { return bufferSize-1; }
 
   // Write the content of the fraction
   numberOfChar += SerializationHelper::Infix(this, buffer+numberOfChar, bufferSize-numberOfChar, floatDisplayMode, numberOfSignificantDigits, "/");
@@ -142,9 +141,6 @@ int FractionLayoutNode::serialize(char * buffer, int bufferSize, Preferences::Pr
 
   // Add system parenthesis
   numberOfChar+= SerializationHelper::CodePoint(buffer + numberOfChar, bufferSize - numberOfChar, UCodePointRightSystemParenthesis);
-  if (numberOfChar >= bufferSize-1) { return bufferSize-1;}
-
-  buffer[numberOfChar] = 0;
   return numberOfChar;
 }
 
diff --git a/poincare/src/integer.cpp b/poincare/src/integer.cpp
index a28e19e0b..431c19697 100644
--- a/poincare/src/integer.cpp
+++ b/poincare/src/integer.cpp
@@ -174,32 +174,32 @@ int Integer::serialize(char * buffer, int bufferSize) const {
   abs.setNegative(false);
   IntegerDivision d = udiv(abs, base);
 
-  int size = 0;
+  int length = 0;
   if (isZero()) {
-    size += SerializationHelper::CodePoint(buffer + size, bufferSize - size, '0');
+    length += SerializationHelper::CodePoint(buffer + length, bufferSize - length, '0');
   } else if (isNegative()) {
-    size += SerializationHelper::CodePoint(buffer + size, bufferSize - size, '-');
+    length += SerializationHelper::CodePoint(buffer + length, bufferSize - length, '-');
   }
 
   while (!(d.remainder.isZero() &&
         d.quotient.isZero())) {
     char c = char_from_digit(d.remainder.isZero() ? 0 : d.remainder.digit(0));
-    if (size >= bufferSize-1) {
+    if (length >= bufferSize-1) {
       return PrintFloat::convertFloatToText<float>(NAN, buffer, bufferSize, PrintFloat::k_numberOfStoredSignificantDigits, Preferences::PrintFloatMode::Decimal);
     }
-    size += SerializationHelper::CodePoint(buffer + size, bufferSize - size, c);
+    length += SerializationHelper::CodePoint(buffer + length, bufferSize - length, c);
     d = udiv(d.quotient, base);
   }
-  assert(size <= bufferSize - 1);
-  buffer[size] = 0;
+  assert(length <= bufferSize - 1);
+  buffer[length] = 0;
 
   // Flip the string
-  for (int i = m_negative, j=size-1 ; i < j ; i++, j--) {
+  for (int i = m_negative, j=length-1 ; i < j ; i++, j--) {
     char c = buffer[i];
     buffer[i] = buffer[j];
     buffer[j] = c;
   }
-  return size;
+  return length;
 }
 
 // Layout
diff --git a/poincare/src/integral_layout.cpp b/poincare/src/integral_layout.cpp
index f3cdd7ce0..862b22ccd 100644
--- a/poincare/src/integral_layout.cpp
+++ b/poincare/src/integral_layout.cpp
@@ -202,7 +202,6 @@ int IntegralLayoutNode::serialize(char * buffer, int bufferSize, Preferences::Pr
 
   // Write the closing system parenthesis
   numberOfChar += SerializationHelper::CodePoint(buffer + numberOfChar, bufferSize - numberOfChar, UCodePointRightSystemParenthesis);
-  buffer[numberOfChar] = 0;
   return numberOfChar;
 }
 
diff --git a/poincare/src/matrix.cpp b/poincare/src/matrix.cpp
index 5d3778733..377255f2a 100644
--- a/poincare/src/matrix.cpp
+++ b/poincare/src/matrix.cpp
@@ -17,6 +17,8 @@
 
 namespace Poincare {
 
+static inline int minInt(int x, int y) { return x < y ? x : y; }
+
 void MatrixNode::didAddChildAtIndex(int newNumberOfChildren) {
   setNumberOfRows(1);
   setNumberOfColumns(newNumberOfChildren);
@@ -41,11 +43,10 @@ int MatrixNode::serialize(char * buffer, int bufferSize, Preferences::PrintFloat
     return -1;
   }
   buffer[bufferSize-1] = 0;
-  int currentChar = 0;
-  if (currentChar >= bufferSize-1) {
+  if (bufferSize == 1) {
     return 0;
   }
-  currentChar += SerializationHelper::CodePoint(buffer + currentChar, bufferSize - currentChar, '[');
+  int currentChar = SerializationHelper::CodePoint(buffer, bufferSize, '[');
   if (currentChar >= bufferSize-1) {
     return currentChar;
   }
@@ -78,11 +79,7 @@ int MatrixNode::serialize(char * buffer, int bufferSize, Preferences::PrintFloat
     }
   }
   currentChar += SerializationHelper::CodePoint(buffer + currentChar, bufferSize - currentChar, ']');
-  if (currentChar >= bufferSize-1) {
-    return currentChar;
-  }
-  buffer[currentChar] = 0;
-  return currentChar;
+  return minInt(currentChar, bufferSize-1);
 }
 
 template<typename T>
diff --git a/poincare/src/matrix_layout.cpp b/poincare/src/matrix_layout.cpp
index d390eea1e..de2ed5e93 100644
--- a/poincare/src/matrix_layout.cpp
+++ b/poincare/src/matrix_layout.cpp
@@ -7,6 +7,8 @@
 
 namespace Poincare {
 
+static inline int minInt(int x, int y) { return x < y ? x : y; }
+
 // MatrixLayoutNode
 
 void MatrixLayoutNode::addGreySquares() {
@@ -98,10 +100,9 @@ int MatrixLayoutNode::serialize(char * buffer, int bufferSize, Preferences::Prin
   }
   buffer[bufferSize-1] = 0;
   if (bufferSize == 1) {
-    return 1;
+    return 0;
   }
-  int numberOfChar = 0;
-  numberOfChar += SerializationHelper::CodePoint(buffer + numberOfChar, bufferSize - numberOfChar, '[');
+  int numberOfChar = SerializationHelper::CodePoint(buffer, bufferSize, '[');
   if (numberOfChar >= bufferSize-1) { return bufferSize-1;}
 
   int maxRowIndex = hasGreySquares() ? m_numberOfRows - 1 : m_numberOfRows;
@@ -117,9 +118,7 @@ int MatrixLayoutNode::serialize(char * buffer, int bufferSize, Preferences::Prin
     if (numberOfChar >= bufferSize-1) { return bufferSize-1; }
   }
   numberOfChar += SerializationHelper::CodePoint(buffer + numberOfChar, bufferSize - numberOfChar, ']');
-  if (numberOfChar >= bufferSize-1) { return bufferSize-1; }
-  buffer[numberOfChar] = 0;
-  return numberOfChar;
+  return minInt(numberOfChar, bufferSize-1);
 }
 
 // Protected
diff --git a/poincare/src/opposite.cpp b/poincare/src/opposite.cpp
index d2531dcf4..bdcba9716 100644
--- a/poincare/src/opposite.cpp
+++ b/poincare/src/opposite.cpp
@@ -56,14 +56,12 @@ int OppositeNode::serialize(char * buffer, int bufferSize, Preferences::PrintFlo
     return -1;
   }
   buffer[bufferSize-1] = 0;
-  int numberOfChar = 0;
   if (bufferSize == 1) { return 0; }
-  numberOfChar += SerializationHelper::CodePoint(buffer + numberOfChar, bufferSize - numberOfChar, '-');
+  int numberOfChar = SerializationHelper::CodePoint(buffer, bufferSize, '-');
   if (numberOfChar >= bufferSize - 1) {
     return bufferSize - 1;
   }
   numberOfChar += childAtIndex(0)->serialize(buffer+numberOfChar, bufferSize-numberOfChar, floatDisplayMode, numberOfSignificantDigits);
-  buffer[numberOfChar] = 0;
   return numberOfChar;
 }
 
diff --git a/poincare/src/print_float.cpp b/poincare/src/print_float.cpp
index 66fc4ad21..6fca595e9 100644
--- a/poincare/src/print_float.cpp
+++ b/poincare/src/print_float.cpp
@@ -59,6 +59,13 @@ void PrintFloat::Long::DivisionByTen(const Long & longToDivide, Long * quotient,
 }
 
 int PrintFloat::Long::serialize(char * buffer, int bufferSize) const {
+  if (bufferSize == 0) {
+    return -1;
+  }
+  buffer[bufferSize-1] = 0;
+  if (bufferSize == 1) {
+    return 0;
+  }
   int numberOfChars = m_negative ? 1 : 0; // 1 for the minus sign char
   if (m_digits[0] != 0) {
     numberOfChars += PrintInt::Left(m_digits[0], buffer + numberOfChars, bufferSize - numberOfChars - 1);
diff --git a/poincare/src/rational.cpp b/poincare/src/rational.cpp
index c4ed722a5..b4920e9ad 100644
--- a/poincare/src/rational.cpp
+++ b/poincare/src/rational.cpp
@@ -72,10 +72,10 @@ int RationalNode::serialize(char * buffer, int bufferSize, Preferences::PrintFlo
   }
   buffer[bufferSize-1] = 0;
   int numberOfChar = signedNumerator().serialize(buffer, bufferSize);
-  if (isInteger()) {
+  if (numberOfChar >= bufferSize-1) {
     return numberOfChar;
   }
-  if (numberOfChar >= bufferSize-1) {
+  if (isInteger()) {
     return numberOfChar;
   }
   numberOfChar += SerializationHelper::CodePoint(buffer + numberOfChar, bufferSize - numberOfChar, '/');
diff --git a/poincare/src/sequence_layout.cpp b/poincare/src/sequence_layout.cpp
index 03f133357..e754fb98a 100644
--- a/poincare/src/sequence_layout.cpp
+++ b/poincare/src/sequence_layout.cpp
@@ -238,7 +238,6 @@ int SequenceLayoutNode::writeDerivedClassInBuffer(const char * operatorName, cha
 
   // Write the closing system parenthesis
   numberOfChar += SerializationHelper::CodePoint(buffer + numberOfChar, bufferSize - numberOfChar, UCodePointRightSystemParenthesis);
-  buffer[numberOfChar] = 0;
   return numberOfChar;
 }
 
diff --git a/poincare/src/serialization_helper.cpp b/poincare/src/serialization_helper.cpp
index ff922b997..cffe218cb 100644
--- a/poincare/src/serialization_helper.cpp
+++ b/poincare/src/serialization_helper.cpp
@@ -76,7 +76,7 @@ int SerializationHelper::SerializeChild(
       return bufferSize-1;
     }
   }
-  buffer[numberOfChar] = 0;
+  assert(buffer[numberOfChar] == 0);
   return numberOfChar;
 }
 
@@ -114,7 +114,8 @@ int InfixPrefix(
     // Add the opening (system or user) parenthesis
     numberOfChar += UTF8Decoder::CodePointToChars(needsSystemParentheses ? UCodePointLeftSystemParenthesis : CodePoint('('), buffer+numberOfChar, bufferSize - numberOfChar);
     if (numberOfChar >= bufferSize-1) {
-      return bufferSize-1;
+      assert(buffer[bufferSize - 1] == 0);
+      return bufferSize - 1;
     }
   }
 
@@ -134,7 +135,7 @@ int InfixPrefix(
           strlcpy(buffer+numberOfChar, operatorName, bufferSize-numberOfChar);
         if (numberOfChar >= bufferSize-1) {
           assert(buffer[bufferSize - 1] == 0);
-          return bufferSize-1;
+          return bufferSize - 1;
         }
       }
       // Write the child, with or without parentheses if needed
@@ -143,26 +144,26 @@ int InfixPrefix(
           numberOfChar += UTF8Decoder::CodePointToChars(UCodePointLeftSystemParenthesis, buffer+numberOfChar, bufferSize - numberOfChar);
           if (numberOfChar >= bufferSize-1) {
             assert(buffer[bufferSize - 1] == 0);
-            return bufferSize-1;
+            return bufferSize - 1;
           }
         }
         numberOfChar += node->childAtIndex(i)->serialize(buffer+numberOfChar, bufferSize-numberOfChar, floatDisplayMode, numberOfDigits);
         if (numberOfChar >= bufferSize-1) {
           assert(buffer[bufferSize - 1] == 0);
-          return bufferSize-1;
+          return bufferSize - 1;
         }
         if (needsSystemParentheses && (childrenCount > 1)) {
           numberOfChar += UTF8Decoder::CodePointToChars(UCodePointRightSystemParenthesis, buffer+numberOfChar, bufferSize - numberOfChar);
           if (numberOfChar >= bufferSize-1) {
             assert(buffer[bufferSize - 1] == 0);
-            return bufferSize-1;
+            return bufferSize - 1;
           }
         }
       } else {
         numberOfChar += SerializationHelper::SerializeChild(node->childAtIndex(i), node, buffer + numberOfChar, bufferSize - numberOfChar, floatDisplayMode, numberOfDigits);
         if (numberOfChar >= bufferSize-1) {
           assert(buffer[bufferSize - 1] == 0);
-          return bufferSize-1;
+          return bufferSize - 1;
         }
       }
     }
@@ -172,11 +173,12 @@ int InfixPrefix(
     // Add the closing system parenthesis
     numberOfChar += UTF8Decoder::CodePointToChars(needsSystemParentheses ? UCodePointRightSystemParenthesis : CodePoint(')'), buffer+numberOfChar, bufferSize - numberOfChar);
     if (numberOfChar >= bufferSize-1) {
-      return bufferSize-1;
+       assert(buffer[bufferSize - 1] == 0);
+       return bufferSize - 1;
     }
   }
 
-  buffer[numberOfChar] = 0;
+  assert(buffer[numberOfChar] == 0);
   return numberOfChar;
 }
 
@@ -217,7 +219,7 @@ int SerializationHelper::CodePoint(char * buffer, int bufferSize, class CodePoin
   if (size <= bufferSize - 1) {
     buffer[size] = 0;
   } else {
-    assert(size -1 == bufferSize - 1);
+    assert(size - 1 == bufferSize - 1);
     buffer[--size] = 0;
   }
   return size;
diff --git a/poincare/src/symbol.cpp b/poincare/src/symbol.cpp
index 2364a05eb..a9d9f2229 100644
--- a/poincare/src/symbol.cpp
+++ b/poincare/src/symbol.cpp
@@ -16,6 +16,8 @@
 
 namespace Poincare {
 
+static inline int minInt(int x, int y) { return x < y ? x : y; }
+
 constexpr char Symbol::k_ans[];
 
 SymbolNode::SymbolNode(const char * newName, int length) : SymbolAbstractNode() {
@@ -108,7 +110,7 @@ int SymbolNode::serialize(char * buffer, int bufferSize, Preferences::PrintFloat
   if (bufferSize == 0) {
     return -1;
   }
-  return strlcpy(buffer, m_name, bufferSize);
+  return minInt(bufferSize - 1, strlcpy(buffer, m_name, bufferSize));
 }
 
 Expression SymbolNode::shallowReduce(ReductionContext reductionContext) {
diff --git a/poincare/src/undefined.cpp b/poincare/src/undefined.cpp
index 7075a18b3..4e9a10b06 100644
--- a/poincare/src/undefined.cpp
+++ b/poincare/src/undefined.cpp
@@ -28,8 +28,7 @@ int UndefinedNode::serialize(char * buffer, int bufferSize, Preferences::PrintFl
   if (bufferSize == 0) {
     return -1;
   }
-  strlcpy(buffer, Undefined::Name(), bufferSize);
-  return minInt(Undefined::NameSize(), bufferSize) - 1;
+  return minInt(strlcpy(buffer, Undefined::Name(), bufferSize), bufferSize - 1);
 }
 
 template<typename T> Evaluation<T> UndefinedNode::templatedApproximate() const {
diff --git a/poincare/src/unreal.cpp b/poincare/src/unreal.cpp
index 9d6c1e0df..c46f3f1a4 100644
--- a/poincare/src/unreal.cpp
+++ b/poincare/src/unreal.cpp
@@ -18,8 +18,7 @@ int UnrealNode::serialize(char * buffer, int bufferSize, Preferences::PrintFloat
   if (bufferSize == 0) {
     return -1;
   }
-  strlcpy(buffer, Unreal::Name(), bufferSize);
-  return minInt(Unreal::NameSize(), bufferSize) - 1;
+  return minInt(strlcpy(buffer, Unreal::Name(), bufferSize), bufferSize - 1);
 }
 
 }
diff --git a/poincare/src/vertical_offset_layout.cpp b/poincare/src/vertical_offset_layout.cpp
index ed5f46cc3..35aec2303 100644
--- a/poincare/src/vertical_offset_layout.cpp
+++ b/poincare/src/vertical_offset_layout.cpp
@@ -8,6 +8,8 @@
 
 namespace Poincare {
 
+static inline int minInt(int x, int y) { return x < y ? x : y; }
+
 void VerticalOffsetLayoutNode::moveCursorLeft(LayoutCursor * cursor, bool * shouldRecomputeLayout) {
   if (cursor->layoutNode() == indiceLayout()
       && cursor->position() == LayoutCursor::Position::Left)
@@ -168,10 +170,9 @@ int VerticalOffsetLayoutNode::serialize(char * buffer, int bufferSize, Preferenc
     if (numberOfChar >= bufferSize-1) { return bufferSize-1; }
 
     numberOfChar += SerializationHelper::CodePoint(buffer+numberOfChar, bufferSize-numberOfChar, '}');
-    if (numberOfChar >= bufferSize-1) { return bufferSize-1; }
-
-    return numberOfChar;
+    return minInt(numberOfChar, bufferSize-1);
   }
+
   assert(m_position == Position::Superscript);
   // If the layout is a superscript, write: '^' 'System(' indice 'System)'
   int numberOfChar = SerializationHelper::CodePoint(buffer, bufferSize, '^');
@@ -181,10 +182,7 @@ int VerticalOffsetLayoutNode::serialize(char * buffer, int bufferSize, Preferenc
   numberOfChar += const_cast<VerticalOffsetLayoutNode *>(this)->indiceLayout()->serialize(buffer+numberOfChar, bufferSize-numberOfChar, floatDisplayMode, numberOfSignificantDigits);
   if (numberOfChar >= bufferSize-1) { return bufferSize-1; }
   numberOfChar += SerializationHelper::CodePoint(buffer+numberOfChar, bufferSize-numberOfChar, UCodePointRightSystemParenthesis);
-  if (numberOfChar >= bufferSize-1) { return bufferSize-1; }
-
-  buffer[numberOfChar] = 0;
-  return numberOfChar;
+  return minInt(numberOfChar, bufferSize-1);
 }
 
 KDSize VerticalOffsetLayoutNode::computeSize() {