diff --git a/apps/apps_container.cpp b/apps/apps_container.cpp
index 134bbe8bd..368818d0c 100644
--- a/apps/apps_container.cpp
+++ b/apps/apps_container.cpp
@@ -114,8 +114,9 @@ VariableBoxController * AppsContainer::variableBoxController() {
 
 void AppsContainer::suspend(bool checkIfPowerKeyReleased) {
   resetShiftAlphaStatus();
+  GlobalPreferences * globalPreferences = GlobalPreferences::sharedGlobalPreferences();
 #ifdef EPSILON_BOOT_PROMPT
-  if (activeApp()->snapshot()!= onBoardingAppSnapshot() && activeApp()->snapshot() != hardwareTestAppSnapshot() && GlobalPreferences::sharedGlobalPreferences()->showPopUp()) {
+  if (activeApp()->snapshot()!= onBoardingAppSnapshot() && activeApp()->snapshot() != hardwareTestAppSnapshot() && globalPreferences->showPopUp()) {
     activeApp()->displayModalViewController(&m_promptController, 0.f, 0.f);
   }
 #endif
@@ -123,7 +124,7 @@ void AppsContainer::suspend(bool checkIfPowerKeyReleased) {
   /* Ion::Power::suspend() completely shuts down the LCD controller. Therefore
    * the frame memory is lost. That's why we need to force a window redraw
    * upon wakeup, otherwise the screen is filled with noise. */
-  Ion::Backlight::setBrightness(GlobalPreferences::sharedGlobalPreferences()->brightnessLevel());
+  Ion::Backlight::setBrightness(globalPreferences->brightnessLevel());
   m_backlightDimmingTimer.reset();
   window()->redraw(true);
 }
diff --git a/apps/calculation/calculation.cpp b/apps/calculation/calculation.cpp
index beb2446a7..240e9b60e 100644
--- a/apps/calculation/calculation.cpp
+++ b/apps/calculation/calculation.cpp
@@ -144,7 +144,8 @@ Calculation::EqualSign Calculation::exactAndApproximateDisplayedOutputsAreEqual(
     return m_equalSign;
   }
   char buffer[k_printedExpressionSize];
-  m_equalSign = exactOutput(context).isEqualToItsApproximationLayout(approximateOutput(context), buffer, k_printedExpressionSize, Preferences::sharedPreferences()->angleUnit(), Preferences::sharedPreferences()->displayMode(), Preferences::sharedPreferences()->numberOfSignificantDigits(), *context) ? EqualSign::Equal : EqualSign::Approximation;
+  Preferences * preferences = Preferences::sharedPreferences();
+  m_equalSign = exactOutput(context).isEqualToItsApproximationLayout(approximateOutput(context), buffer, k_printedExpressionSize, preferences->angleUnit(), preferences->displayMode(), preferences->numberOfSignificantDigits(), *context) ? EqualSign::Equal : EqualSign::Approximation;
   return m_equalSign;
 }
 
diff --git a/apps/global_preferences.cpp b/apps/global_preferences.cpp
index 6c93c5e0c..ddc5d5709 100644
--- a/apps/global_preferences.cpp
+++ b/apps/global_preferences.cpp
@@ -1,15 +1,5 @@
 #include "global_preferences.h"
 
-GlobalPreferences::GlobalPreferences() :
-  m_language(I18n::Language::EN),
-  m_examMode(ExamMode::Desactivate),
-#ifdef EPSILON_BOOT_PROMPT
-  m_showPopUp(true),
-#endif
-  m_brightnessLevel(Ion::Backlight::MaxBrightness)
-{
-}
-
 GlobalPreferences * GlobalPreferences::sharedGlobalPreferences() {
   static GlobalPreferences globalPreferences;
   return &globalPreferences;
@@ -20,9 +10,7 @@ I18n::Language GlobalPreferences::language() const {
 }
 
 void GlobalPreferences::setLanguage(I18n::Language language) {
-  if (language != m_language) {
-    m_language = language;
-  }
+  m_language = language;
 }
 
 GlobalPreferences::ExamMode GlobalPreferences::examMode() const {
@@ -30,17 +18,13 @@ GlobalPreferences::ExamMode GlobalPreferences::examMode() const {
 }
 
 void GlobalPreferences::setExamMode(ExamMode examMode) {
-  if (examMode != m_examMode) {
-    m_examMode = examMode;
-  }
+  m_examMode = examMode;
 }
 
 #ifdef EPSILON_BOOT_PROMPT
 
 void GlobalPreferences::setShowPopUp(bool showPopUp) {
-  if (showPopUp != m_showPopUp) {
-    m_showPopUp = showPopUp;
-  }
+  m_showPopUp = showPopUp;
 }
 
 #endif
diff --git a/apps/global_preferences.h b/apps/global_preferences.h
index 35c7af844..361ee5047 100644
--- a/apps/global_preferences.h
+++ b/apps/global_preferences.h
@@ -9,7 +9,6 @@ public:
     Activate,
     Desactivate
   };
-  GlobalPreferences();
   static GlobalPreferences * sharedGlobalPreferences();
   I18n::Language language() const;
   void setLanguage(I18n::Language language);
@@ -23,6 +22,13 @@ public:
   void setBrightnessLevel(int brightnessLevel);
   constexpr static int NumberOfBrightnessStates = 5;
 private:
+  GlobalPreferences() :
+    m_language(I18n::Language::EN),
+    m_examMode(ExamMode::Desactivate),
+#ifdef EPSILON_BOOT_PROMPT
+    m_showPopUp(true),
+#endif
+    m_brightnessLevel(Ion::Backlight::MaxBrightness) {}
   I18n::Language m_language;
   ExamMode m_examMode;
 #ifdef EPSILON_BOOT_PROMPT
diff --git a/apps/sequence/sequence.cpp b/apps/sequence/sequence.cpp
index 87a68b7ed..cae5ba05a 100644
--- a/apps/sequence/sequence.cpp
+++ b/apps/sequence/sequence.cpp
@@ -261,12 +261,13 @@ T Sequence::approximateToNextRank(int n, SequenceContext * sqctx) const {
   Poincare::Symbol vn1Symbol(Symbol::SpecialSymbols::vn1);
   Poincare::Symbol unSymbol(Symbol::SpecialSymbols::un);
   Poincare::Symbol un1Symbol(Symbol::SpecialSymbols::un1);
+  Preferences * preferences = Poincare::Preferences::sharedPreferences();
   switch (m_type) {
     case Type::Explicit:
     {
       ctx.setValueForSymbol(un, unSymbol);
       ctx.setValueForSymbol(vn, vnSymbol);
-      return expression(sqctx).approximateWithValueForSymbol(symbol(), (T)n, ctx, Poincare::Preferences::sharedPreferences()->angleUnit());
+      return expression(sqctx).approximateWithValueForSymbol(symbol(), (T)n, ctx, preferences->angleUnit());
     }
     case Type::SingleRecurrence:
     {
@@ -277,7 +278,7 @@ T Sequence::approximateToNextRank(int n, SequenceContext * sqctx) const {
       ctx.setValueForSymbol(unm1, unSymbol);
       ctx.setValueForSymbol(vn, vn1Symbol);
       ctx.setValueForSymbol(vnm1, vnSymbol);
-      return expression(sqctx).approximateWithValueForSymbol(symbol(), (T)(n-1), ctx, Poincare::Preferences::sharedPreferences()->angleUnit());
+      return expression(sqctx).approximateWithValueForSymbol(symbol(), (T)(n-1), ctx, preferences->angleUnit());
     }
     default:
     {
@@ -291,7 +292,7 @@ T Sequence::approximateToNextRank(int n, SequenceContext * sqctx) const {
       ctx.setValueForSymbol(unm2, unSymbol);
       ctx.setValueForSymbol(vnm1, vn1Symbol);
       ctx.setValueForSymbol(vnm2, vnSymbol);
-      return expression(sqctx).approximateWithValueForSymbol(symbol(), (T)(n-2), ctx, Poincare::Preferences::sharedPreferences()->angleUnit());
+      return expression(sqctx).approximateWithValueForSymbol(symbol(), (T)(n-2), ctx, preferences->angleUnit());
     }
   }
 }
diff --git a/apps/settings/main_controller.cpp b/apps/settings/main_controller.cpp
index 0ca243151..8b8ab6a50 100644
--- a/apps/settings/main_controller.cpp
+++ b/apps/settings/main_controller.cpp
@@ -69,6 +69,7 @@ void MainController::didBecomeFirstResponder() {
 }
 
 bool MainController::handleEvent(Ion::Events::Event event) {
+  GlobalPreferences * globalPreferences = GlobalPreferences::sharedGlobalPreferences();
   if (m_messageTreeModel->children(selectedRow())->numberOfChildren() == 0) {
 #if EPSILON_BOOT_PROMPT == EPSILON_BETA_PROMPT
     if (m_messageTreeModel->children(selectedRow())->label() == I18n::Message::BetaPopUp) {
@@ -77,7 +78,7 @@ bool MainController::handleEvent(Ion::Events::Event event) {
 #endif
 #ifdef EPSILON_BOOT_PROMPT
       if (event == Ion::Events::OK || event == Ion::Events::EXE) {
-        GlobalPreferences::sharedGlobalPreferences()->setShowPopUp(!GlobalPreferences::sharedGlobalPreferences()->showPopUp());
+        globalPreferences->setShowPopUp(!globalPreferences->showPopUp());
         m_selectableTableView.reloadCellAtLocation(m_selectableTableView.selectedColumn(), m_selectableTableView.selectedRow());
         return true;
       }
@@ -88,7 +89,7 @@ bool MainController::handleEvent(Ion::Events::Event event) {
       if (event == Ion::Events::Right || event == Ion::Events::Left || event == Ion::Events::Plus || event == Ion::Events::Minus) {
         int delta = Ion::Backlight::MaxBrightness/GlobalPreferences::NumberOfBrightnessStates;
         int direction = (event == Ion::Events::Right || event == Ion::Events::Plus) ? delta : -delta;
-        GlobalPreferences::sharedGlobalPreferences()->setBrightnessLevel(GlobalPreferences::sharedGlobalPreferences()->brightnessLevel()+direction);
+        globalPreferences->setBrightnessLevel(globalPreferences->brightnessLevel()+direction);
         m_selectableTableView.reloadCellAtLocation(m_selectableTableView.selectedColumn(), m_selectableTableView.selectedRow());
         return true;
       }
@@ -184,16 +185,18 @@ int MainController::typeAtLocation(int i, int j) {
 }
 
 void MainController::willDisplayCellForIndex(HighlightCell * cell, int index) {
+  GlobalPreferences * globalPreferences = GlobalPreferences::sharedGlobalPreferences();
+  Preferences * preferences = Preferences::sharedPreferences();
   MessageTableCell * myCell = (MessageTableCell *)cell;
   myCell->setMessage(m_messageTreeModel->children(index)->label());
   if (index == 4) {
     MessageTableCellWithGauge * myGaugeCell = (MessageTableCellWithGauge *)cell;
     GaugeView * myGauge = (GaugeView *)myGaugeCell->accessoryView();
-    myGauge->setLevel((float)GlobalPreferences::sharedGlobalPreferences()->brightnessLevel()/(float)Ion::Backlight::MaxBrightness);
+    myGauge->setLevel((float)globalPreferences->brightnessLevel()/(float)Ion::Backlight::MaxBrightness);
     return;
   }
   if (index == 5) {
-    int index = (int)GlobalPreferences::sharedGlobalPreferences()->language()-1;
+    int index = (int)globalPreferences->language()-1;
     static_cast<MessageTableCellWithChevronAndMessage *>(cell)->setSubtitle(I18n::LanguageNames[index]);
     return;
   }
@@ -201,7 +204,7 @@ void MainController::willDisplayCellForIndex(HighlightCell * cell, int index) {
   if (index == 7) {
     MessageTableCellWithSwitch * mySwitchCell = (MessageTableCellWithSwitch *)cell;
     SwitchView * mySwitch = (SwitchView *)mySwitchCell->accessoryView();
-    mySwitch->setState(GlobalPreferences::sharedGlobalPreferences()->showPopUp());
+    mySwitch->setState(globalPreferences->showPopUp());
     return;
   }
 #endif
@@ -209,16 +212,16 @@ void MainController::willDisplayCellForIndex(HighlightCell * cell, int index) {
   int childIndex = -1;
   switch (index) {
     case 0:
-      childIndex = (int)Preferences::sharedPreferences()->angleUnit();
+      childIndex = (int)preferences->angleUnit();
       break;
     case 1:
-      childIndex = (int)Preferences::sharedPreferences()->displayMode();
+      childIndex = (int)preferences->displayMode();
       break;
     case 2:
-      childIndex = (int)Preferences::sharedPreferences()->editionMode();
+      childIndex = (int)preferences->editionMode();
       break;
     case 3:
-      childIndex = (int)Preferences::sharedPreferences()->complexFormat();
+      childIndex = (int)preferences->complexFormat();
       break;
   }
   I18n::Message message = childIndex >= 0 ? m_messageTreeModel->children(index)->children(childIndex)->label() : I18n::Message::Default;
diff --git a/apps/settings/sub_menu/preferences_controller.cpp b/apps/settings/sub_menu/preferences_controller.cpp
index bc6c5d8a6..3305d8fd5 100644
--- a/apps/settings/sub_menu/preferences_controller.cpp
+++ b/apps/settings/sub_menu/preferences_controller.cpp
@@ -109,32 +109,34 @@ void PreferencesController::willDisplayCellForIndex(HighlightCell * cell, int in
 }
 
 void PreferencesController::setPreferenceWithValueIndex(I18n::Message message, int valueIndex) {
+  Preferences * preferences = Preferences::sharedPreferences();
   if (message == I18n::Message::AngleUnit) {
-    Preferences::sharedPreferences()->setAngleUnit((Preferences::AngleUnit)valueIndex);
+    preferences->setAngleUnit((Preferences::AngleUnit)valueIndex);
   }
   if (message == I18n::Message::DisplayMode) {
-    Preferences::sharedPreferences()->setDisplayMode((Preferences::PrintFloatMode)valueIndex);
+    preferences->setDisplayMode((Preferences::PrintFloatMode)valueIndex);
   }
   if (message == I18n::Message::EditionMode) {
-    Preferences::sharedPreferences()->setEditionMode((Preferences::EditionMode)valueIndex);
+    preferences->setEditionMode((Preferences::EditionMode)valueIndex);
   }
   if (message == I18n::Message::ComplexFormat) {
-    Preferences::sharedPreferences()->setComplexFormat((Preferences::ComplexFormat)valueIndex);
+    preferences->setComplexFormat((Preferences::ComplexFormat)valueIndex);
   }
 }
 
 int PreferencesController::valueIndexForPreference(I18n::Message message) {
+  Preferences * preferences = Preferences::sharedPreferences();
   if (message == I18n::Message::AngleUnit) {
-    return (int)Preferences::sharedPreferences()->angleUnit();
+    return (int)preferences->angleUnit();
   }
   if (message == I18n::Message::DisplayMode) {
-    return (int)Preferences::sharedPreferences()->displayMode();
+    return (int)preferences->displayMode();
   }
   if (message == I18n::Message::EditionMode) {
-    return (int)Preferences::sharedPreferences()->editionMode();
+    return (int)preferences->editionMode();
   }
   if (message == I18n::Message::ComplexFormat) {
-    return (int)Preferences::sharedPreferences()->complexFormat();
+    return (int)preferences->complexFormat();
   }
   return 0;
 }
diff --git a/apps/solver/equation_store.cpp b/apps/solver/equation_store.cpp
index 10ce4b447..765dd69e0 100644
--- a/apps/solver/equation_store.cpp
+++ b/apps/solver/equation_store.cpp
@@ -119,8 +119,9 @@ EquationStore::Error EquationStore::exactSolve(Poincare::Context * context) {
   Expression coefficients[k_maxNumberOfEquations][Expression::k_maxNumberOfVariables];
   Expression constants[k_maxNumberOfEquations];
   bool isLinear = true; // Invalid the linear system if one equation is non-linear
+  Preferences * preferences = Preferences::sharedPreferences();
   for (int i = 0; i < numberOfDefinedModels(); i++) {
-    isLinear = isLinear && definedModelAtIndex(i)->standardForm(context).getLinearCoefficients(m_variables, coefficients[i], &constants[i], *context, Preferences::sharedPreferences()->angleUnit());
+    isLinear = isLinear && definedModelAtIndex(i)->standardForm(context).getLinearCoefficients(m_variables, coefficients[i], &constants[i], *context, preferences->angleUnit());
     if (!isLinear) {
     // TODO: should we clean pool allocated memory if the system is not linear
 #if 0
@@ -151,7 +152,7 @@ EquationStore::Error EquationStore::exactSolve(Poincare::Context * context) {
     assert(numberOfVariables == 1 && numberOfDefinedModels() == 1);
     char x = m_variables[0];
     Expression polynomialCoefficients[Expression::k_maxNumberOfPolynomialCoefficients];
-    int degree = definedModelAtIndex(0)->standardForm(context).getPolynomialReducedCoefficients(x, polynomialCoefficients, *context, Preferences::sharedPreferences()->angleUnit());
+    int degree = definedModelAtIndex(0)->standardForm(context).getPolynomialReducedCoefficients(x, polynomialCoefficients, *context, preferences->angleUnit());
     if (degree == 2) {
       /* Polynomial degree <= 2*/
       m_type = Type::PolynomialMonovariable;
@@ -179,7 +180,7 @@ EquationStore::Error EquationStore::exactSolve(Poincare::Context * context) {
       /* Check for equality between exact and approximate layouts */
       if (!m_exactSolutionIdentity[i]) {
         char buffer[Shared::ExpressionModel::k_expressionBufferSize];
-        m_exactSolutionEquality[i] = exactSolutions[i].isEqualToItsApproximationLayout(approximate, buffer, Shared::ExpressionModel::k_expressionBufferSize, Preferences::sharedPreferences()->angleUnit(), Preferences::sharedPreferences()->displayMode(), Preferences::sharedPreferences()->numberOfSignificantDigits(), *context);
+        m_exactSolutionEquality[i] = exactSolutions[i].isEqualToItsApproximationLayout(approximate, buffer, Shared::ExpressionModel::k_expressionBufferSize, preferences->angleUnit(), preferences->displayMode(), preferences->numberOfSignificantDigits(), *context);
       }
     }
   }
diff --git a/apps/title_bar_view.cpp b/apps/title_bar_view.cpp
index 44bddcc41..097895e57 100644
--- a/apps/title_bar_view.cpp
+++ b/apps/title_bar_view.cpp
@@ -84,10 +84,11 @@ void TitleBarView::refreshPreferences() {
   constexpr size_t bufferSize = 13;
   char buffer[bufferSize];
   int numberOfChar = 0;
-  if (Preferences::sharedPreferences()->displayMode() == Preferences::PrintFloatMode::Scientific) {
+  Preferences * preferences = Preferences::sharedPreferences();
+  if (preferences->displayMode() == Preferences::PrintFloatMode::Scientific) {
     numberOfChar += strlcpy(buffer, I18n::translate(I18n::Message::Sci), bufferSize);
   }
-  if (Preferences::sharedPreferences()->angleUnit() == Preferences::AngleUnit::Radian) {
+  if (preferences->angleUnit() == Preferences::AngleUnit::Radian) {
     numberOfChar += strlcpy(buffer+numberOfChar, I18n::translate(I18n::Message::Rad), bufferSize - numberOfChar);
   } else {
     numberOfChar += strlcpy(buffer+numberOfChar, I18n::translate(I18n::Message::Deg), bufferSize - numberOfChar);
diff --git a/poincare/src/global_context.cpp b/poincare/src/global_context.cpp
index bd43d8fc6..3d3c3887f 100644
--- a/poincare/src/global_context.cpp
+++ b/poincare/src/global_context.cpp
@@ -43,7 +43,8 @@ void GlobalContext::setExpressionForSymbolName(const Expression & expression, co
   FileName symbolFileName = fileNameForSymbol(symbol);
 
   // evaluate before deleting anything (to be able to evaluate A+2->A)
-  Expression evaluation = expression.isUninitialized() ? Expression() : expression.approximate<double>(context, Preferences::sharedPreferences()->angleUnit(), Preferences::sharedPreferences()->complexFormat());
+  Preferences * preferences = Preferences::sharedPreferences();
+  Expression evaluation = expression.isUninitialized() ? Expression() : expression.approximate<double>(context, preferences->angleUnit(), preferences->complexFormat());
   // Delete any record with same name (as it is going to be override)
   Ion::Storage::sharedStorage()->recordNamed(symbolFileName.nameWithExtension).destroy();