diff --git a/Detector/UT/include/Detector/UT/DeUTSector.h b/Detector/UT/include/Detector/UT/DeUTSector.h
index 0d0e693a81f9228d1ff131694e61a3200925bbaa..843920214a7f15c778289ffd78391c603d768462 100644
--- a/Detector/UT/include/Detector/UT/DeUTSector.h
+++ b/Detector/UT/include/Detector/UT/DeUTSector.h
@@ -188,6 +188,7 @@ namespace LHCb::Detector::UT {
     using DeIOVElement::DeIOVElement;
 
     unsigned int firstStrip() const { return this->access()->m_sensor.m_firstStrip; }
+    unsigned int lastStrip() const { return sensor().lastStrip(); }
     unsigned int firstBeetle() const { return this->access()->m_firstBeetle; }
     unsigned int nStrip() const { return this->access()->m_sensor.m_nStrip; }
     bool         stripflip() const { return this->access()->m_sensor.m_stripflip; }
@@ -215,7 +216,7 @@ namespace LHCb::Detector::UT {
       return sensor().trajectory( strip, offset );
     }
     LineTraj<double> trajectoryFirstStrip() const { return createTraj( firstStrip(), 0. ); }
-    LineTraj<double> trajectoryLastStrip() const { return createTraj( nStrip() - 1u + firstStrip(), 0. ); }
+    LineTraj<double> trajectoryLastStrip() const { return createTraj( lastStrip(), 0. ); }
 
     ROOT::Math::XYZPoint globalCentre() const { return this->toGlobal( ROOT::Math::XYZPoint( 0.0, 0.0, 0.0 ) ); }
 
@@ -575,7 +576,7 @@ namespace LHCb::Detector::UT {
     void trajectory( unsigned int strip, double offset, double& dxdy, double& dzdy, double& xAtYEq0, double& zAtYEq0,
                      double& ybegin, double& yend ) const {
       auto i         = offset + strip;
-      auto numstrips = ( ( stripflip() && xInverted() ) ? ( nStrip() - i ) : i );
+      auto numstrips = ( ( stripflip() && xInverted() ) ? ( lastStrip() - i ) : i );
 
       dxdy    = this->access()->m_dxdy;
       dzdy    = this->access()->m_dzdy;
diff --git a/Detector/UT/include/Detector/UT/DeUTSensor.h b/Detector/UT/include/Detector/UT/DeUTSensor.h
index 650d700be12d117f2c2468e2c07e0b464a48a1cf..5a93d9759aa7178b62218cd67d5e7fb9761a70e3 100644
--- a/Detector/UT/include/Detector/UT/DeUTSensor.h
+++ b/Detector/UT/include/Detector/UT/DeUTSensor.h
@@ -89,26 +89,23 @@ namespace LHCb::Detector::UT {
     float        activeHeight() const { return fabs( this->access()->m_vMinLocal - this->access()->m_vMaxLocal ); }
     bool         getStripflip() const { return this->access()->m_stripflip; }
     unsigned int firstStrip() const { return this->access()->m_firstStrip; };
+    unsigned int lastStrip() const { return nStrip() - 1u + firstStrip(); };
     unsigned int version() const { return this->access()->m_version; };
 
     using DeIOVElement::DeIOVElement;
 
     bool contains( const ChannelID aChannel ) const { return ( aChannel == channelID() ); }
 
-    bool isStrip( const unsigned int strip ) const {
-      return ( strip >= firstStrip() ) && strip < nStrip() + firstStrip();
-    }
+    bool isStrip( const unsigned int strip ) const { return ( strip >= firstStrip() ) && strip <= lastStrip(); }
     LineTraj<double> trajectory( unsigned int strip, double offset ) const {
       if ( this->access()->m_useCorrectP0Parameter && !isStrip( strip ) ) {
-        throw std::out_of_range(
-            fmt::format( "DeUTSector::createTraj: strip out of range, given {strip}, expect [{first}, {last}]",
-                         fmt::arg( "strip", strip ), fmt::arg( "first", firstStrip() ),
-                         fmt::arg( "last", firstStrip() + nStrip() - 1 ) ) );
+        throw std::out_of_range( fmt::format(
+            "DeUTSector::createTraj: strip out of range, given {strip}, expect [{first}, {last}]",
+            fmt::arg( "strip", strip ), fmt::arg( "first", firstStrip() ), fmt::arg( "last", lastStrip() ) ) );
       }
-      const double arclen =
-          ( ( xInverted() && getStripflip() ) ? ( nStrip() - offset - strip - ( firstStrip() + 1 ) % 2 )
-                                              : ( offset + strip - firstStrip() ) ) *
-          pitch();
+      const double arclen = ( ( xInverted() && getStripflip() ) ? ( lastStrip() - ( offset + strip ) )
+                                                                : ( ( offset + strip ) - firstStrip() ) ) *
+                            pitch();
       ROOT::Math::XYZPoint midPoint =
           this->access()->m_midTraj->position( arclen + this->access()->m_midTraj->beginRange() );
       return { midPoint, this->access()->m_direction, this->access()->m_range,