diff --git a/apps/graph/function.cpp b/apps/graph/function.cpp
index 95ac5065f..ee39131a3 100644
--- a/apps/graph/function.cpp
+++ b/apps/graph/function.cpp
@@ -4,6 +4,7 @@
 namespace Graph {
 
 Function::Function(const char * text, KDColor color) :
+  m_text(""),
   m_name(text),
   m_color(color),
   m_expression(nullptr),
@@ -22,7 +23,10 @@ void Function::setContent(const char * c) {
   if (m_layout != nullptr) {
     delete m_layout;
   }
-  m_layout = expression()->createLayout();
+  m_layout = nullptr;
+  if (m_expression) {
+    m_layout = expression()->createLayout();
+  }
 }
 
 void Function::setColor(KDColor color) {
diff --git a/apps/graph/function_store.cpp b/apps/graph/function_store.cpp
index 754eb1db8..c51203d28 100644
--- a/apps/graph/function_store.cpp
+++ b/apps/graph/function_store.cpp
@@ -23,7 +23,22 @@ Function * FunctionStore::activeFunctionAtIndex(int i) {
   assert(i>=0 && i<m_numberOfFunctions);
   int index = 0;
   for (int k = 0; k < m_numberOfFunctions; k++) {
-    if (m_functions[k].isActive()) {
+    if (m_functions[k].isActive() && m_functions[k].layout() != nullptr) {
+      if (i == index) {
+        return &m_functions[k];
+      }
+      index++;
+    }
+  }
+  assert(false);
+  return nullptr;
+}
+
+Function * FunctionStore::definedFunctionAtIndex(int i) {
+  assert(i>=0 && i<m_numberOfFunctions);
+  int index = 0;
+  for (int k = 0; k < m_numberOfFunctions; k++) {
+    if (m_functions[k].layout() != nullptr) {
       if (i == index) {
         return &m_functions[k];
       }
@@ -71,6 +86,16 @@ int FunctionStore::numberOfActiveFunctions() {
   return result;
 }
 
+int FunctionStore::numberOfDefinedFunctions() {
+  int result = 0;
+  for (int i = 0; i < m_numberOfFunctions; i++) {
+    if (m_functions[i].layout() != nullptr) {
+      result++;
+    }
+  }
+  return result;
+}
+
 const char *  FunctionStore::firstAvailableName() {
   for (int k = 0; k < k_maxNumberOfFunctions; k++) {
     int j = 0;
diff --git a/apps/graph/function_store.h b/apps/graph/function_store.h
index ff04efde8..0f0b4ba7b 100644
--- a/apps/graph/function_store.h
+++ b/apps/graph/function_store.h
@@ -11,9 +11,11 @@ public:
   FunctionStore();
   Function * functionAtIndex(int i);
   Function * activeFunctionAtIndex(int i);
+  Function * definedFunctionAtIndex(int i);
   Function * addEmptyFunction();
   void removeFunction(Function * f);
   int numberOfFunctions();
+  int numberOfDefinedFunctions();
   int numberOfActiveFunctions();
 
 private:
diff --git a/apps/graph/graph/graph_view.cpp b/apps/graph/graph/graph_view.cpp
index 9ec9733c1..99d550ddc 100644
--- a/apps/graph/graph/graph_view.cpp
+++ b/apps/graph/graph/graph_view.cpp
@@ -163,8 +163,8 @@ void GraphView::drawFunction(KDContext * ctx, KDRect rect) const {
 
   for (KDCoordinate px = rect.x()-stampSize; px<rect.right(); px++) {
     float x = pixelToFloat(Axis::Horizontal, px);
-    for (int i=0; i<m_functionStore->numberOfFunctions(); i++) {
-      Function * f = m_functionStore->functionAtIndex(i);
+    for (int i=0; i<m_functionStore->numberOfDefinedFunctions(); i++) {
+      Function * f = m_functionStore->definedFunctionAtIndex(i);
       if (f->isActive()) {
         float y = f->evaluateAtAbscissa(x, m_evaluateContext);
         KDCoordinate py = floatToPixel(Axis::Vertical, y);
diff --git a/apps/graph/list/function_expression_view.cpp b/apps/graph/list/function_expression_view.cpp
index cc96889a7..4f780af21 100644
--- a/apps/graph/list/function_expression_view.cpp
+++ b/apps/graph/list/function_expression_view.cpp
@@ -9,6 +9,9 @@ FunctionExpressionView::FunctionExpressionView() :
 
 void FunctionExpressionView::drawRect(KDContext * ctx, KDRect rect) const {
   EvenOddCell::drawRect(ctx, rect);
+  if (m_function->layout() == nullptr) {
+    return;
+  }
   // Select the background color according to the even line and the cursor selection
   KDColor background = backgroundColor();
   // Select text color according to the state of the function
diff --git a/apps/graph/list/function_name_view.cpp b/apps/graph/list/function_name_view.cpp
index 65509fb92..b59d4768e 100644
--- a/apps/graph/list/function_name_view.cpp
+++ b/apps/graph/list/function_name_view.cpp
@@ -28,9 +28,13 @@ void FunctionNameView::drawRect(KDContext * ctx, KDRect rect) const {
   KDColor background = backgroundColor();
   // Position the name of the function
   const char * functionName = m_function->name();
-  KDCoordinate baseline = m_function->layout()->baseline();
   KDSize textSize = KDText::stringSize(functionName);
-  KDSize expressionSize = m_function->layout()->size();
+  KDCoordinate baseline = textSize.height();
+  KDSize expressionSize = textSize;
+  if (m_function->layout()) {
+    baseline = m_function->layout()->baseline();
+    expressionSize = m_function->layout()->size();
+  }
   KDPoint origin(0.5f*(k_colorIndicatorThickness + m_frame.width() - 4*textSize.width()),
     baseline-textSize.height()+0.5f*(m_frame.height() - expressionSize.height()));
   ctx->drawString(functionName, origin, functionNameColor, background);
diff --git a/apps/graph/list/list_controller.cpp b/apps/graph/list/list_controller.cpp
index 99288b494..1bb9acf6e 100644
--- a/apps/graph/list/list_controller.cpp
+++ b/apps/graph/list/list_controller.cpp
@@ -25,7 +25,7 @@ Responder * ListController::tabController() const{
 }
 
 int ListController::numberOfRows() {
-  return m_functionStore->numberOfFunctions();
+  return 1 + m_functionStore->numberOfFunctions();
 };
 
 int ListController::numberOfColumns() {
@@ -33,7 +33,13 @@ int ListController::numberOfColumns() {
 };
 
 KDCoordinate ListController::rowHeight(int j) {
+  if (j == numberOfRows() - 1) {
+    return k_emptyRowHeight;
+  }
   Function * function = m_functionStore->functionAtIndex(j);
+  if (function->layout() == nullptr) {
+    return k_emptyRowHeight;
+  }
   KDCoordinate functionSize = function->layout()->size().height();
   return functionSize + k_verticalFunctionMargin;
 }
diff --git a/apps/graph/list/list_controller.h b/apps/graph/list/list_controller.h
index 068a6695d..12bca26c8 100644
--- a/apps/graph/list/list_controller.h
+++ b/apps/graph/list/list_controller.h
@@ -38,6 +38,7 @@ public:
 private:
   static constexpr KDCoordinate k_verticalFunctionMargin = 50-12;
   static constexpr KDCoordinate k_functionNameWidth = 65;
+  static constexpr KDCoordinate k_emptyRowHeight = 50;
   Responder * tabController() const;
   constexpr static int k_maxNumberOfRows = 6;
   // !!! CAUTION: The order here is important
diff --git a/apps/graph/values/values_controller.cpp b/apps/graph/values/values_controller.cpp
index ce4215d44..a9b48a753 100644
--- a/apps/graph/values/values_controller.cpp
+++ b/apps/graph/values/values_controller.cpp
@@ -99,9 +99,9 @@ int ValuesController::numberOfRows() {
 
 int ValuesController::numberOfColumns() {
   int result = 1;
-  for (int i = 0; i < m_functionStore->numberOfFunctions(); i++) {
-    if (m_functionStore->functionAtIndex(i)->isActive()) {
-      result += 1 + m_functionStore->functionAtIndex(i)->displayDerivative();
+  for (int i = 0; i < m_functionStore->numberOfDefinedFunctions(); i++) {
+    if (m_functionStore->definedFunctionAtIndex(i)->isActive()) {
+      result += 1 + m_functionStore->definedFunctionAtIndex(i)->displayDerivative();
     }
   }
   return result;
@@ -426,15 +426,15 @@ void ValuesController::willDisplayCellAtLocation(View * cell, int i, int j) {
 Function * ValuesController::functionAtColumn(int i) {
   assert(i > 0);
   int index = 1;
-  for (int k = 0; k < m_functionStore->numberOfFunctions(); k++) {
-    if (m_functionStore->functionAtIndex(k)->isActive()) {
+  for (int k = 0; k < m_functionStore->numberOfDefinedFunctions(); k++) {
+    if (m_functionStore->definedFunctionAtIndex(k)->isActive()) {
       if (i == index) {
-        return m_functionStore->functionAtIndex(k);
+        return m_functionStore->definedFunctionAtIndex(k);
       }
       index++;
-      if (m_functionStore->functionAtIndex(k)->displayDerivative()) {
+      if (m_functionStore->definedFunctionAtIndex(k)->displayDerivative()) {
         if (i == index) {
-          return m_functionStore->functionAtIndex(k);
+          return m_functionStore->definedFunctionAtIndex(k);
         }
         index++;
       }
@@ -447,13 +447,13 @@ Function * ValuesController::functionAtColumn(int i) {
 bool ValuesController::isDerivativeColumn(int i) {
   assert(i >= 1);
   int index = 1;
-  for (int k = 0; k < m_functionStore->numberOfFunctions(); k++) {
-    if (m_functionStore->functionAtIndex(k)->isActive()) {
+  for (int k = 0; k < m_functionStore->numberOfDefinedFunctions(); k++) {
+    if (m_functionStore->definedFunctionAtIndex(k)->isActive()) {
       if (i == index) {
         return false;
       }
       index++;
-      if (m_functionStore->functionAtIndex(k)->displayDerivative()) {
+      if (m_functionStore->definedFunctionAtIndex(k)->displayDerivative()) {
         if (i == index) {
           return true;
         }
diff --git a/poincare/src/expression.cpp b/poincare/src/expression.cpp
index a7e70f4de..861c387d5 100644
--- a/poincare/src/expression.cpp
+++ b/poincare/src/expression.cpp
@@ -14,6 +14,9 @@ Expression::~Expression() {
 }
 
 Expression * Expression::parse(char const * string) {
+  if (string[0] == 0) {
+    return nullptr;
+  }
   YY_BUFFER_STATE buf = poincare_expression_yy_scan_string(string);
   Expression * expression = 0;
   poincare_expression_yyparse(&expression);