diff --git a/apps/sequence/graph/graph_controller.cpp b/apps/sequence/graph/graph_controller.cpp
index d5686e5ca..d16d68e9d 100644
--- a/apps/sequence/graph/graph_controller.cpp
+++ b/apps/sequence/graph/graph_controller.cpp
@@ -29,6 +29,10 @@ TermSumController * GraphController::termSumController() {
   return &m_termSumController;
 }
 
+int GraphController::numberOfCurves() const {
+  return m_sequenceStore->numberOfModels();
+}
+
 BannerView * GraphController::bannerView() {
   return &m_bannerView;
 }
diff --git a/apps/sequence/graph/graph_controller.h b/apps/sequence/graph/graph_controller.h
index 7c6916c0d..40e7f70d8 100644
--- a/apps/sequence/graph/graph_controller.h
+++ b/apps/sequence/graph/graph_controller.h
@@ -17,6 +17,8 @@ public:
   GraphController(Responder * parentResponder, InputEventHandlerDelegate * inputEventHandlerDelegate, SequenceStore * sequenceStore, CurveViewRange * graphRange, Shared::CurveViewCursor * cursor, int * indexFunctionSelectedByCursor, uint32_t * modelVersion, uint32_t * rangeVersion, Poincare::Preferences::AngleUnit * angleUnitVersion, ButtonRowController * header);
   I18n::Message emptyMessage() override;
   TermSumController * termSumController();
+protected:
+  int numberOfCurves() const override;
 private:
   BannerView * bannerView() override;
   bool handleEnter() override;
diff --git a/apps/shared/interactive_curve_view_controller.h b/apps/shared/interactive_curve_view_controller.h
index 27079c950..e455a6457 100644
--- a/apps/shared/interactive_curve_view_controller.h
+++ b/apps/shared/interactive_curve_view_controller.h
@@ -50,7 +50,7 @@ protected:
   virtual bool closestCurveIndexIsSuitable(int newIndex, int currentIndex) const { assert(false); return false; }
   virtual double yValue(int curveIndex, double x, Poincare::Context * context) const { assert(false); return 0; }
   virtual bool suitableYValue(double y) const { return true; }
-  virtual int numberOfCurves() const { assert(false); return 0; }
+  virtual int numberOfCurves() const = 0;
 
   OkView m_okView;
 private: