diff --git a/Trigger/TrigAlgorithms/TrigL2MuonSA/TrigL2MuonSA/AlphaBetaEstimate.h b/Trigger/TrigAlgorithms/TrigL2MuonSA/TrigL2MuonSA/AlphaBetaEstimate.h
index 9504cc4bea4f2dc7f63dcf2fc8d22751491734f7..cec9c148b5814183574ec738e3ec672589de656a 100644
--- a/Trigger/TrigAlgorithms/TrigL2MuonSA/TrigL2MuonSA/AlphaBetaEstimate.h
+++ b/Trigger/TrigAlgorithms/TrigL2MuonSA/TrigL2MuonSA/AlphaBetaEstimate.h
@@ -50,10 +50,10 @@ class AlphaBetaEstimate: public AthAlgTool
 			      double MiddleSlope, double MiddleR, double MiddleZ,
 			      double sign);
     
-    double     computeRadius3Points(double InnerZ, double InnerR, double EEZ, double EER,double MiddleZ, double MiddleR );
-    double     calcDistance(double x1,double y1,double x2,double y2,double x3,double y3) ;
+    double     computeRadius3Points(double InnerZ, double InnerR, double EEZ, double EER,double MiddleZ, double MiddleR ) const ;
+    double     calcDistance(double x1,double y1,double x2,double y2,double x3,double y3) const;
     
-    inline bool isZero( float value, float tolerance = 1e-5 ) {
+    inline bool isZero( float value, float tolerance = 1e-5 ) const {
       return std::abs( value ) < tolerance;
     }
     
diff --git a/Trigger/TrigAlgorithms/TrigL2MuonSA/src/AlphaBetaEstimate.cxx b/Trigger/TrigAlgorithms/TrigL2MuonSA/src/AlphaBetaEstimate.cxx
index 87834d7910af9cf539f460f120b1da7969851a98..1c1fef6ce9fe8703e7532bc640188191a5a5b364 100644
--- a/Trigger/TrigAlgorithms/TrigL2MuonSA/src/AlphaBetaEstimate.cxx
+++ b/Trigger/TrigAlgorithms/TrigL2MuonSA/src/AlphaBetaEstimate.cxx
@@ -343,7 +343,7 @@ double TrigL2MuonSA::AlphaBetaEstimate::computeRadius(double InnerSlope, double
 double TrigL2MuonSA::AlphaBetaEstimate::computeRadius3Points(double InnerZ, double InnerR, 
                                                                double EEZ, double EER,
                                                                double MiddleZ, double MiddleR)
-{
+const {
   double radius_EE;
 
   double a3;
@@ -377,7 +377,7 @@ double TrigL2MuonSA::AlphaBetaEstimate::computeRadius3Points(double InnerZ, doub
   return radius_EE;
 }
 
-double TrigL2MuonSA::AlphaBetaEstimate::calcDistance(double x1,double y1,double x2,double y2,double x3,double y3)    {
+double TrigL2MuonSA::AlphaBetaEstimate::calcDistance(double x1,double y1,double x2,double y2,double x3,double y3)   const {
   double xm1=(x1+x2)/2;
   double xm2=(x2+x3)/2;
   double ym1=(y1+y2)/2;