diff --git a/apps/regression/model/cubic_model.h b/apps/regression/model/cubic_model.h
index 7a6ee8b25..0a41dae2f 100644
--- a/apps/regression/model/cubic_model.h
+++ b/apps/regression/model/cubic_model.h
@@ -14,7 +14,7 @@ public:
   double evaluate(double * modelCoefficients, double x) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
-  double numberOfCoefficients() const override { return 4; }
+  int numberOfCoefficients() const override { return 4; }
 };
 
 }
diff --git a/apps/regression/model/exponential_model.h b/apps/regression/model/exponential_model.h
index 9d06547d5..d51e00bb9 100644
--- a/apps/regression/model/exponential_model.h
+++ b/apps/regression/model/exponential_model.h
@@ -14,7 +14,7 @@ public:
   double evaluate(double * modelCoefficients, double x) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
-  double numberOfCoefficients() const override { return 2; }
+  int numberOfCoefficients() const override { return 2; }
 };
 
 }
diff --git a/apps/regression/model/linear_model.h b/apps/regression/model/linear_model.h
index e9074b0cb..0249a841d 100644
--- a/apps/regression/model/linear_model.h
+++ b/apps/regression/model/linear_model.h
@@ -15,7 +15,7 @@ public:
   double levelSet(double * modelCoefficients, double y) const override;
   virtual void fit(Store * store, int series, double * modelCoefficients, Poincare::Context * context) override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
-  double numberOfCoefficients() const override { return 2; }
+  int numberOfCoefficients() const override { return 2; }
 };
 
 }
diff --git a/apps/regression/model/logarithmic_model.h b/apps/regression/model/logarithmic_model.h
index 7dadad93f..7e8dc6954 100644
--- a/apps/regression/model/logarithmic_model.h
+++ b/apps/regression/model/logarithmic_model.h
@@ -14,7 +14,7 @@ public:
   double evaluate(double * modelCoefficients, double x) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
-  double numberOfCoefficients() const override { return 2; }
+  int numberOfCoefficients() const override { return 2; }
 };
 
 }
diff --git a/apps/regression/model/logistic_model.h b/apps/regression/model/logistic_model.h
index c504da2a6..6450ba116 100644
--- a/apps/regression/model/logistic_model.h
+++ b/apps/regression/model/logistic_model.h
@@ -14,7 +14,7 @@ public:
   double evaluate(double * modelCoefficients, double x) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
-  double numberOfCoefficients() const override { return 3; }
+  int numberOfCoefficients() const override { return 3; }
 };
 
 }
diff --git a/apps/regression/model/model.h b/apps/regression/model/model.h
index ba9064d04..ee5065a19 100644
--- a/apps/regression/model/model.h
+++ b/apps/regression/model/model.h
@@ -31,7 +31,7 @@ public:
   virtual double evaluate(double * modelCoefficients, double x) const = 0;
   virtual double levelSet(double * modelCoefficients, double y) const = 0;
   virtual void fit(Store * store, int series, double * modelCoefficients, Poincare::Context * context);
-  virtual double numberOfCoefficients() const = 0;
+  virtual int numberOfCoefficients() const = 0;
 private:
   // Model attributes
   virtual double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const = 0;
diff --git a/apps/regression/model/power_model.h b/apps/regression/model/power_model.h
index ae4592825..86a3390e0 100644
--- a/apps/regression/model/power_model.h
+++ b/apps/regression/model/power_model.h
@@ -14,7 +14,7 @@ public:
   double evaluate(double * modelCoefficients, double x) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
-  double numberOfCoefficients() const override { return 2; }
+  int numberOfCoefficients() const override { return 2; }
 };
 
 }
diff --git a/apps/regression/model/quadratic_model.h b/apps/regression/model/quadratic_model.h
index edb589cae..3d35b3ad3 100644
--- a/apps/regression/model/quadratic_model.h
+++ b/apps/regression/model/quadratic_model.h
@@ -14,7 +14,7 @@ public:
   double evaluate(double * modelCoefficients, double x) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
-  double numberOfCoefficients() const override { return 3; }
+  int numberOfCoefficients() const override { return 3; }
 };
 
 }
diff --git a/apps/regression/model/quartic_model.h b/apps/regression/model/quartic_model.h
index ba41b207a..087d3369a 100644
--- a/apps/regression/model/quartic_model.h
+++ b/apps/regression/model/quartic_model.h
@@ -14,7 +14,7 @@ public:
   double evaluate(double * modelCoefficients, double x) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
-  double numberOfCoefficients() const override { return 5; }
+  int numberOfCoefficients() const override { return 5; }
 };
 
 }
diff --git a/apps/regression/model/trigonometric_model.h b/apps/regression/model/trigonometric_model.h
index fa50a7aac..a2f14e62a 100644
--- a/apps/regression/model/trigonometric_model.h
+++ b/apps/regression/model/trigonometric_model.h
@@ -14,7 +14,7 @@ public:
   double evaluate(double * modelCoefficients, double x) const override;
   double levelSet(double * modelCoefficients, double y) const override;
   double partialDerivate(double * modelCoefficients, int derivateCoefficientIndex, double x) const override;
-  double numberOfCoefficients() const override { return 3; }
+  int numberOfCoefficients() const override { return 3; }
 };
 
 }