diff --git a/Code/MultiTemporal/otbTimeSeries.h b/Code/MultiTemporal/otbTimeSeries.h
index 0a136f023afb8c3f2609cc019ecf29cc170f895f..0d8c98129d251c3a04debdf2092e9fba84618e06 100644
--- a/Code/MultiTemporal/otbTimeSeries.h
+++ b/Code/MultiTemporal/otbTimeSeries.h
@@ -55,7 +55,7 @@ public:
     return m_Coefficients;
   }
 
-  inline CoefficientsPrecisionType GetValue( CoefficientsPrecisionType val)
+  inline CoefficientsPrecisionType GetValue( CoefficientsPrecisionType val) const
   {
     CoefficientsPrecisionType tmpVal = 0;
     for( unsigned int i=0; i<=TDegree; ++i)