diff --git a/apps/graph/graph/calculation_graph_controller.cpp b/apps/graph/graph/calculation_graph_controller.cpp
index 91f0823d4..0f745fe7f 100644
--- a/apps/graph/graph/calculation_graph_controller.cpp
+++ b/apps/graph/graph/calculation_graph_controller.cpp
@@ -63,7 +63,7 @@ void CalculationGraphController::setRecord(Ion::Storage::Record record) {
 
 void CalculationGraphController::reloadBannerView() {
   m_bannerView->setNumberOfSubviews(2);
-  reloadBannerViewForCursorOnFunction(m_cursor, m_record, functionStore(),  'x');
+  reloadBannerViewForCursorOnFunction(m_cursor, m_record, functionStore(), StorageCartesianFunctionStore::Symbol());
 }
 
 bool CalculationGraphController::moveCursor(int direction) {
diff --git a/apps/graph/graph/graph_controller_helper.cpp b/apps/graph/graph/graph_controller_helper.cpp
index 78d8d1964..67f52f61d 100644
--- a/apps/graph/graph/graph_controller_helper.cpp
+++ b/apps/graph/graph/graph_controller_helper.cpp
@@ -23,7 +23,7 @@ void GraphControllerHelper::reloadDerivativeInBannerViewForCursorOnFunction(Shar
   constexpr size_t bufferSize = FunctionBannerDelegate::k_maxNumberOfCharacters+PrintFloat::bufferSizeForFloatsWithPrecision(Constant::LargeNumberOfSignificantDigits);
   char buffer[bufferSize];
   const char * space = " ";
-  int numberOfChar = function->derivativeNameWithArgument(buffer, bufferSize, 'x');
+  int numberOfChar = function->derivativeNameWithArgument(buffer, bufferSize, StorageCartesianFunctionStore::Symbol());
   const char * legend = "=";
   numberOfChar += strlcpy(buffer+numberOfChar, legend, bufferSize-numberOfChar);
   double y = function->approximateDerivative(cursor->x(), app->localContext());
diff --git a/apps/graph/graph/integral_graph_controller.cpp b/apps/graph/graph/integral_graph_controller.cpp
index a64e24c0a..36d7491b9 100644
--- a/apps/graph/graph/integral_graph_controller.cpp
+++ b/apps/graph/graph/integral_graph_controller.cpp
@@ -40,7 +40,7 @@ Layout IntegralGraphController::createFunctionLayout(StorageFunction * function)
   constexpr size_t bufferSize = SymbolAbstract::k_maxNameSize+5; // f(x)dx
   char buffer[bufferSize];
   const char * dx = "dx";
-  int numberOfChars = function->nameWithArgument(buffer, bufferSize-strlen(dx), 'x');
+  int numberOfChars = function->nameWithArgument(buffer, bufferSize-strlen(dx), StorageCartesianFunctionStore::Symbol());
   strlcpy(buffer+numberOfChars, dx, bufferSize-numberOfChars);
   return LayoutHelper::String(buffer, strlen(buffer), KFont::SmallFont);
 }
diff --git a/apps/graph/graph/intersection_graph_controller.cpp b/apps/graph/graph/intersection_graph_controller.cpp
index 16c831aca..caf58fcd5 100644
--- a/apps/graph/graph/intersection_graph_controller.cpp
+++ b/apps/graph/graph/intersection_graph_controller.cpp
@@ -18,18 +18,18 @@ const char * IntersectionGraphController::title() {
 
 void IntersectionGraphController::reloadBannerView() {
   m_bannerView->setNumberOfSubviews(2);
-  reloadBannerViewForCursorOnFunction(m_cursor, m_record, functionStore(), 'x');
+  reloadBannerViewForCursorOnFunction(m_cursor, m_record, functionStore(), StorageCartesianFunctionStore::Symbol());
   constexpr size_t bufferSize = FunctionBannerDelegate::k_maxNumberOfCharacters+Poincare::PrintFloat::bufferSizeForFloatsWithPrecision(Constant::LargeNumberOfSignificantDigits);
   char buffer[bufferSize];
   const char * space = "                  ";
   const char * legend = "=";
   // 'f(x)=g(x)=', keep 2 chars for '='
   StorageCartesianFunction * f = functionStore()->modelForRecord(m_record);
-  int numberOfChar = f->nameWithArgument(buffer, bufferSize-2, 'x');
+  int numberOfChar = f->nameWithArgument(buffer, bufferSize-2, StorageCartesianFunctionStore::Symbol());
   numberOfChar += strlcpy(buffer+numberOfChar, legend, bufferSize-numberOfChar);
   // keep 1 char for '=';
   StorageCartesianFunction * g = functionStore()->modelForRecord(m_intersectedRecord);
-  numberOfChar += g->nameWithArgument(buffer, bufferSize-numberOfChar-1, 'x');
+  numberOfChar += g->nameWithArgument(buffer, bufferSize-numberOfChar-1, StorageCartesianFunctionStore::Symbol());
   numberOfChar += strlcpy(buffer+numberOfChar, legend, bufferSize-numberOfChar);
   numberOfChar += PoincareHelpers::ConvertFloatToText<double>(m_cursor->y(), buffer+numberOfChar, bufferSize-numberOfChar, Constant::MediumNumberOfSignificantDigits);
   strlcpy(buffer+numberOfChar, space, bufferSize-numberOfChar);
diff --git a/apps/graph/graph/tangent_graph_controller.cpp b/apps/graph/graph/tangent_graph_controller.cpp
index 8947b146c..9f6a01c1e 100644
--- a/apps/graph/graph/tangent_graph_controller.cpp
+++ b/apps/graph/graph/tangent_graph_controller.cpp
@@ -40,7 +40,7 @@ void TangentGraphController::reloadBannerView() {
     return;
   }
   App * myApp = static_cast<App *>(app());
-  StorageFunctionBannerDelegate::reloadBannerViewForCursorOnFunction(m_cursor, m_record, myApp->functionStore(), 'x');
+  StorageFunctionBannerDelegate::reloadBannerViewForCursorOnFunction(m_cursor, m_record, myApp->functionStore(), StorageCartesianFunctionStore::Symbol());
   GraphControllerHelper::reloadDerivativeInBannerViewForCursorOnFunction(m_cursor, m_record, myApp);
   constexpr size_t bufferSize = FunctionBannerDelegate::k_maxNumberOfCharacters+PrintFloat::bufferSizeForFloatsWithPrecision(Constant::LargeNumberOfSignificantDigits);
   char buffer[bufferSize];
diff --git a/apps/graph/storage_cartesian_function_store.h b/apps/graph/storage_cartesian_function_store.h
index 8875acf26..c23a8a129 100644
--- a/apps/graph/storage_cartesian_function_store.h
+++ b/apps/graph/storage_cartesian_function_store.h
@@ -11,7 +11,8 @@ namespace Graph {
 class StorageCartesianFunctionStore : public Shared::StorageFunctionStore {
 public:
   Shared::StorageCartesianFunction * modelForRecord(Ion::Storage::Record record) const override { return static_cast<Shared::StorageCartesianFunction *>(Shared::StorageFunctionStore::modelForRecord(record)); }
-  char symbol() const override { return 'x'; }
+  static char Symbol() { return 'x'; }
+  char symbol() const override { return Symbol(); }
 private:
   Ion::Storage::Record::ErrorStatus addEmptyModel() override;
   const char * modelExtension() const override { return Shared::GlobalContext::funcExtension; }
diff --git a/apps/graph/values/storage_derivative_parameter_controller.cpp b/apps/graph/values/storage_derivative_parameter_controller.cpp
index 021476cd2..067033b61 100644
--- a/apps/graph/values/storage_derivative_parameter_controller.cpp
+++ b/apps/graph/values/storage_derivative_parameter_controller.cpp
@@ -18,7 +18,7 @@ StorageDerivativeParameterController::StorageDerivativeParameterController(Stora
 }
 
 const char * StorageDerivativeParameterController::title() {
-  functionStore()->modelForRecord(m_record)->derivativeNameWithArgument(m_pageTitle, k_maxNumberOfCharsInTitle, 'x');
+  functionStore()->modelForRecord(m_record)->derivativeNameWithArgument(m_pageTitle, k_maxNumberOfCharsInTitle, StorageCartesianFunctionStore::Symbol());
   return m_pageTitle;
 }
 
diff --git a/apps/graph/values/storage_function_parameter_controller.cpp b/apps/graph/values/storage_function_parameter_controller.cpp
index 0d914a0c1..767ab9fbe 100644
--- a/apps/graph/values/storage_function_parameter_controller.cpp
+++ b/apps/graph/values/storage_function_parameter_controller.cpp
@@ -8,7 +8,7 @@ using namespace Shared;
 namespace Graph {
 
 StorageFunctionParameterController::StorageFunctionParameterController(StorageValuesController * valuesController) :
-  StorageValuesFunctionParameterController('x'),
+  StorageValuesFunctionParameterController(StorageCartesianFunctionStore::Symbol()),
   m_displayDerivativeColumn(I18n::Message::DerivativeFunctionColumn),
   m_valuesController(valuesController)
 {
diff --git a/apps/graph/values/storage_values_controller.cpp b/apps/graph/values/storage_values_controller.cpp
index 7f47a9b64..76f666804 100644
--- a/apps/graph/values/storage_values_controller.cpp
+++ b/apps/graph/values/storage_values_controller.cpp
@@ -45,9 +45,9 @@ void StorageValuesController::willDisplayCellAtLocation(HighlightCell * cell, in
     const size_t bufferNameSize = Shared::StorageFunction::k_maxNameWithArgumentSize + 1;
     char bufferName[bufferNameSize];
     if (isDerivativeColumn(i)) {
-      function->derivativeNameWithArgument(bufferName, bufferNameSize, 'x');
+      function->derivativeNameWithArgument(bufferName, bufferNameSize, StorageCartesianFunctionStore::Symbol());
     } else {
-      function->nameWithArgument(bufferName, bufferNameSize, 'x');
+      function->nameWithArgument(bufferName, bufferNameSize, StorageCartesianFunctionStore::Symbol());
     }
     myFunctionCell->setText(bufferName);
     myFunctionCell->setColor(function->color());
diff --git a/apps/variable_box_controller.cpp b/apps/variable_box_controller.cpp
index 318186ce9..8a0711e99 100644
--- a/apps/variable_box_controller.cpp
+++ b/apps/variable_box_controller.cpp
@@ -3,6 +3,7 @@
 #include "shared/poincare_helpers.h"
 #include "shared/storage_function.h"
 #include "shared/storage_cartesian_function.h"
+#include "graph/storage_cartesian_function_store.h"
 #include "constant.h"
 #include <escher/metric.h>
 #include <assert.h>
@@ -91,7 +92,7 @@ void VariableBoxController::willDisplayCellForIndex(HighlightCell * cell, int in
   } else {
     assert(m_currentPage == Page::Function);
     StorageCartesianFunction f(record);
-    symbolLength = f.nameWithArgument(symbolName, Shared::StorageFunction::k_maxNameWithArgumentSize, 'x');
+    symbolLength = f.nameWithArgument(symbolName, Shared::StorageFunction::k_maxNameWithArgumentSize, Graph::StorageCartesianFunctionStore::Symbol());
   }
   Layout symbolLayout = LayoutHelper::String(symbolName, symbolLength);
   myCell->setLayout(symbolLayout);
diff --git a/apps/variable_box_empty_controller.cpp b/apps/variable_box_empty_controller.cpp
index 96b115858..4fda1f659 100644
--- a/apps/variable_box_empty_controller.cpp
+++ b/apps/variable_box_empty_controller.cpp
@@ -1,5 +1,6 @@
 #include "variable_box_empty_controller.h"
 #include <poincare/layout_helper.h>
+#include "graph/storage_cartesian_function_store.h"
 #include "i18n.h"
 #include <assert.h>
 
@@ -88,7 +89,7 @@ void VariableBoxEmptyController::setType(Type type) {
     case Type::Functions:
     {
       message = I18n::Message::EmptyFunctionBox;
-      char storeFunction[] = {'3', '+', 'x', Ion::Charset::Sto, 'f', '(', 'x', ')', 0};
+      char storeFunction[] = {'3', '+', Graph::StorageCartesianFunctionStore::Symbol(), Ion::Charset::Sto, 'f', '(', Graph::StorageCartesianFunctionStore::Symbol(), ')', 0};
       layout = LayoutHelper::String(storeFunction, sizeof(storeFunction)-1, KDText::FontSize::Small);
       break;
     }