diff --git a/src/math/FGNelderMead.h b/src/math/FGNelderMead.h
index ca6188cdd3864738d98b9b62409627a38f7124ca..5ded8614da109e34df6507d9f6537981514303dc 100644
--- a/src/math/FGNelderMead.h
+++ b/src/math/FGNelderMead.h
@@ -67,7 +67,7 @@ private:
     std::vector<double> m_cost;
     std::vector<double> m_elemSum;
     bool m_showSimplex;
-	bool m_status;
+	int m_status;
     const std::vector<double> & initialGuess;
     const std::vector<double> & initialStepSize;
 	int iterMax, iter;