diff --git a/Phys/DaVinciFilters/CMakeLists.txt b/Phys/DaVinciFilters/CMakeLists.txt
index 43d95a44a52f8ecaf4acc4e2a3617c3c9f690d50..a2d5c76269bbbd18e98918e3925c020ceaea93db 100644
--- a/Phys/DaVinciFilters/CMakeLists.txt
+++ b/Phys/DaVinciFilters/CMakeLists.txt
@@ -43,7 +43,7 @@ gaudi_add_module(DaVinciFilters
         Phys::DaVinciInterfacesLib
         Phys::DaVinciKernelLib
         Phys::DaVinciTypesLib
-        Phys::DecayTreeFitter
+        Phys::DecayTreeFitterLib
         Phys::LoKiArrayFunctorsLib
         Phys::LoKiPhysLib
         Rec::TrackInterfacesLib
diff --git a/Phys/DecayTreeFitter/CMakeLists.txt b/Phys/DecayTreeFitter/CMakeLists.txt
index 07f062c4503c2275e2fa19d72619ac61c4d2d3ed..a6dc6aff1550f69022b0e7caa1498821381065b0 100644
--- a/Phys/DecayTreeFitter/CMakeLists.txt
+++ b/Phys/DecayTreeFitter/CMakeLists.txt
@@ -13,35 +13,36 @@ Phys/DecayTreeFitter
 --------------------
 #]=======================================================================]
 
-gaudi_add_library(DecayTreeFitter
+gaudi_add_library(DecayTreeFitterLib
     SOURCES
-        src/Constraint.cpp
-        src/ConvertedPhoton.cpp
-        src/DecayChain.cpp
-        src/FitParams.cpp
-        src/Fitter.cpp
-        src/HelixUtils.cpp
-        src/InteractionPoint.cpp
-        src/InternalParticle.cpp
-        src/InternalRecoTrack.cpp
-        src/JetMomentum.cpp
-        src/KalmanCalculator.cpp
-        src/MergedConstraint.cpp
-        src/MissingParticle.cpp
-        src/ParticleBase.cpp
-        src/RecoComposite.cpp
-        src/RecoMergedPi0.cpp
-        src/RecoParticle.cpp
-        src/RecoPhoton.cpp
-        src/RecoResonance.cpp
-        src/RecoTrack.cpp
-        src/Resonance.cpp
-        src/VtxErrCode.cpp
+        src/lib/Constraint.cpp
+        src/lib/ConvertedPhoton.cpp
+        src/lib/DecayChain.cpp
+        src/lib/FitParams.cpp
+        src/lib/Fitter.cpp
+        src/lib/HelixUtils.cpp
+        src/lib/InteractionPoint.cpp
+        src/lib/InternalParticle.cpp
+        src/lib/InternalRecoTrack.cpp
+        src/lib/JetMomentum.cpp
+        src/lib/KalmanCalculator.cpp
+        src/lib/MergedConstraint.cpp
+        src/lib/MissingParticle.cpp
+        src/lib/ParticleBase.cpp
+        src/lib/RecoComposite.cpp
+        src/lib/RecoMergedPi0.cpp
+        src/lib/RecoParticle.cpp
+        src/lib/RecoPhoton.cpp
+        src/lib/RecoResonance.cpp
+        src/lib/RecoTrack.cpp
+        src/lib/Resonance.cpp
+        src/lib/VtxErrCode.cpp
     LINK
         PUBLIC
             Gaudi::GaudiKernel
             LHCb::LHCbMathLib
             Phys::DaVinciTypesLib
+            Phys::DaVinciInterfacesLib
             Rec::TrackInterfacesLib
         PRIVATE
             Boost::headers
@@ -55,8 +56,19 @@ gaudi_add_library(DecayTreeFitter
             Rec::TrackKernel
 )
 
+gaudi_add_module(DecayTreeFitter
+    SOURCES
+        src/component/DecayTreeFitterAlg.cpp
+    LINK
+        Gaudi::GaudiAlgLib
+        LHCb::LHCbKernel
+        LHCb::PhysEvent
+        DecayTreeFitterLib
+        LHCb::LinkerEvent
+)
+
 gaudi_add_dictionary(DecayTreeFitterDict
     HEADERFILES dict/DecayTreeFitterDict.h
     SELECTION dict/DecayTreeFitterDict.xml
-    LINK DecayTreeFitter
+    LINK DecayTreeFitterLib
 )
diff --git a/Phys/DecayTreeFitter/src/component/DecayTreeFitterAlg.cpp b/Phys/DecayTreeFitter/src/component/DecayTreeFitterAlg.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..c64665ac0c32bdf04d53d57cd9babbabad04c3e8
--- /dev/null
+++ b/Phys/DecayTreeFitter/src/component/DecayTreeFitterAlg.cpp
@@ -0,0 +1,159 @@
+/*****************************************************************************\
+* (c) Copyright 2021 CERN for the benefit of the LHCb Collaboration           *
+*                                                                             *
+* This software is distributed under the terms of the GNU General Public      *
+* Licence version 3 (GPL Version 3), copied verbatim in the file "COPYING".   *
+*                                                                             *
+* In applying this licence, CERN does not waive the privileges and immunities *
+* granted to it by virtue of its status as an Intergovernmental Organization  *
+* or submit itself to any jurisdiction.                                       *
+\*****************************************************************************/
+// ============================================================================
+// Include files
+
+#include "DecayTreeFitter/Fitter.h"
+#include "DetDesc/IDetectorElement.h"
+#include "Event/Particle.h"
+#include "GaudiAlg/Transformer.h"
+#include "Kernel/DecayTree.h"
+#include "Kernel/IParticleDescendants.h"
+#include "Kernel/IPrintDecay.h"
+#include "Kernel/ParticleID.h"
+#include "Relations/Relation1D.h"
+
+#include "TrackInterfaces/ITrackStateProvider.h"
+#include <cassert>
+
+namespace {
+  using Table = LHCb::Relation1D<LHCb::Particle, LHCb::Particle>;
+  using out_t = std::tuple<LHCb::Particles, Table>;
+} // namespace
+// ============================================================================
+/** @class DecayTreeFitterAlg
+ *  Algorithm that runs DecayTreeFitter on an input and stores the output.
+ *  Can be used stand-alone as part of a selection, or in conjuction with MAP_INPUT functor
+ *
+ *  @param Input Location of particles
+ *  @returns Output Location of DecayTreeFit-ed particles
+ *  @returns OutputRelations location of relation table between in and out particles
+ *
+ * Properties:
+ *  - "PrintTree" = false: print decay tree (useful for debugging)
+ *
+ * Use:
+ *  @code
+ *     from PyConf.Algorithms import DecayTreeFitterAlg
+ *     import Functors as F
+ *     DTF = DecayTreeFitterAlg(Input=dimuons, MassConstraints=["J/psi(1S)"])
+ *     DTFRelations = DTF.OutputRelations  # Relations
+ *     functor = F.MAP_INPUT(Functor=F.MASS, Relations=DTFRelations)
+ *  @endcode
+ *
+ *  @see DecayTreeFitter::Fitter
+ *  @see FunTuple
+ *  @see ParticleMapper_Rel
+ *  @author Patrick Koppenburg
+ *  @date 2021-07-19
+ */
+class DecayTreeFitterAlg : public Gaudi::Functional::MultiTransformer<out_t( LHCb::Particles const& )> {
+public:
+  // ==========================================================================
+  /** the standard constructor
+   *  @param name algorithm instance name
+   *  @param pSvc service locator
+   */
+  DecayTreeFitterAlg( const std::string& name, ISvcLocator* pSvc )
+      : MultiTransformer( name, pSvc, {KeyValue{"Input", ""}},
+                          {KeyValue{"Output", ""}, KeyValue{"OutputRelations", ""}} ) {}
+  // ==========================================================================
+  /// the standard execution of the algorithm
+  // ==========================================================================
+  out_t operator()( const LHCb::Particles& parts ) const override {
+    auto lhcb = getDet<IDetectorElement>( m_standardGeometry_address );
+    if ( !lhcb ) { throw GaudiException( "Could not load geometry", name(), StatusCode::FAILURE ); }
+    auto& geometry = *lhcb->geometry();
+
+    // output
+    LHCb::Particles parts_out;
+    Table           p2p_out;
+
+    for ( auto* p : parts ) {
+      DecayTreeFitter::Fitter fitter( *p, m_stateprovider ); // @todo also foresee the case with a PV given
+      if ( !m_massConstraints.empty() ) {
+        for ( const auto& C : m_massConstraints ) { fitter.setMassConstraint( LHCb::ParticleID( C ) ); }
+      }
+      fitter.fit( geometry );
+      LHCb::DecayTree fittedTree = fitter.getFittedTree();
+      if ( fittedTree.valid() ) {
+        m_fittedCount++;
+        if ( m_print ) m_printDecay->printTree( fittedTree.head(), -1 );
+
+        // fill relations. First get decay tree of input
+        LHCb::Particle::ConstVector parts_in; // input tree, flattened
+        parts_in.push_back( p );              // input mother
+        LHCb::Particle::ConstVector dauts_in = m_descendants->descendants( p );
+        parts_in.insert( parts_in.end(), dauts_in.begin(), dauts_in.end() ); // insert descendants
+
+        // search for fitted particles in flattened tree
+        for ( const auto inP : parts_in ) {
+          // 1. Find refitted partner in tree
+          auto* clone = fittedTree.findClone( *inP );
+          if ( !clone ) {
+            err() << "No refitted particle found for a " << inP->particleID().pid() << endmsg;
+            throw GaudiException( "No refitted particle found for", name(), StatusCode::FAILURE );
+          }
+          LHCb::Particle* refittedP = clone->clone(); // get fitted particle
+
+          // 2. save partner in output
+          LHCb::Particles::key_type key =
+              parts_out.insert( refittedP ); // insert, but not yet release as this would delete the clone map
+          const LHCb::Particle* savedP = static_cast<const LHCb::Particle*>(
+              parts_out.containedObject( key ) ); // get pointer to newly instered particle
+
+          // 3. relate
+          p2p_out.relate( inP, savedP ).ignore();
+        }
+        fittedTree.release(); // release now
+
+      } else {
+        m_failedCount++;
+        Warning( "Failed fit", StatusCode::SUCCESS, 0 ).ignore();
+      }
+    }
+    if ( !parts.empty() ) {
+      m_eventCount++;
+      m_candidateCount += parts.size();
+      m_fittedCount += parts_out.size();
+    }
+
+    return std::make_tuple( std::move( parts_out ), p2p_out );
+  }
+
+private:
+  // ==========================================================================
+  // tools
+  ToolHandle<ITrackStateProvider>  m_stateprovider{this, "StateProvider", "TrackStateProvider"};
+  ToolHandle<IParticleDescendants> m_descendants{this, "Descendants", "ParticleDescendants"};
+  ToolHandle<IPrintDecay>          m_printDecay{this, "PrintDecayTreeTool", "PrintDecayTreeTool"};
+  // properties
+  Gaudi::Property<std::vector<int>> m_massConstraints{this, "MassConstraints"};
+  Gaudi::Property<std::string>      m_standardGeometry_address{this, "StandardGeometryTop", "/dd/Structure/LHCb"};
+  // Gaudi::Property<bool>               m_originVertex{this, "ConstrainToOriginVertex", false};
+  Gaudi::Property<bool> m_print{this, "PrintTree", false};
+
+  // counters
+  mutable Gaudi::Accumulators::Counter<>                 m_eventCount{this, "Events"};
+  mutable Gaudi::Accumulators::StatCounter<unsigned int> m_candidateCount{this, "Input Particles"};
+  mutable Gaudi::Accumulators::StatCounter<unsigned int> m_fittedCount{this, "Fitted Particles"};
+  mutable Gaudi::Accumulators::StatCounter<unsigned int> m_failedCount{this, "Failed fits"};
+  mutable Gaudi::Accumulators::StatCounter<unsigned int> m_savedCount{this, "saved Particles"};
+
+  // ==========================================================================
+};
+
+// ============================================================================
+/// declare the factory (needed for instantiation)
+DECLARE_COMPONENT( DecayTreeFitterAlg )
+// ============================================================================
+// The END
+// ============================================================================
diff --git a/Phys/DecayTreeFitter/src/Configuration.h b/Phys/DecayTreeFitter/src/lib/Configuration.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/Configuration.h
rename to Phys/DecayTreeFitter/src/lib/Configuration.h
diff --git a/Phys/DecayTreeFitter/src/Constraint.cpp b/Phys/DecayTreeFitter/src/lib/Constraint.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/Constraint.cpp
rename to Phys/DecayTreeFitter/src/lib/Constraint.cpp
diff --git a/Phys/DecayTreeFitter/src/Constraint.h b/Phys/DecayTreeFitter/src/lib/Constraint.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/Constraint.h
rename to Phys/DecayTreeFitter/src/lib/Constraint.h
diff --git a/Phys/DecayTreeFitter/src/ConvertedPhoton.cpp b/Phys/DecayTreeFitter/src/lib/ConvertedPhoton.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/ConvertedPhoton.cpp
rename to Phys/DecayTreeFitter/src/lib/ConvertedPhoton.cpp
diff --git a/Phys/DecayTreeFitter/src/ConvertedPhoton.h b/Phys/DecayTreeFitter/src/lib/ConvertedPhoton.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/ConvertedPhoton.h
rename to Phys/DecayTreeFitter/src/lib/ConvertedPhoton.h
diff --git a/Phys/DecayTreeFitter/src/DecayChain.cpp b/Phys/DecayTreeFitter/src/lib/DecayChain.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/DecayChain.cpp
rename to Phys/DecayTreeFitter/src/lib/DecayChain.cpp
diff --git a/Phys/DecayTreeFitter/src/DecayChain.h b/Phys/DecayTreeFitter/src/lib/DecayChain.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/DecayChain.h
rename to Phys/DecayTreeFitter/src/lib/DecayChain.h
diff --git a/Phys/DecayTreeFitter/src/FitParams.cpp b/Phys/DecayTreeFitter/src/lib/FitParams.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/FitParams.cpp
rename to Phys/DecayTreeFitter/src/lib/FitParams.cpp
diff --git a/Phys/DecayTreeFitter/src/FitParams.h b/Phys/DecayTreeFitter/src/lib/FitParams.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/FitParams.h
rename to Phys/DecayTreeFitter/src/lib/FitParams.h
diff --git a/Phys/DecayTreeFitter/src/Fitter.cpp b/Phys/DecayTreeFitter/src/lib/Fitter.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/Fitter.cpp
rename to Phys/DecayTreeFitter/src/lib/Fitter.cpp
diff --git a/Phys/DecayTreeFitter/src/HelixUtils.cpp b/Phys/DecayTreeFitter/src/lib/HelixUtils.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/HelixUtils.cpp
rename to Phys/DecayTreeFitter/src/lib/HelixUtils.cpp
diff --git a/Phys/DecayTreeFitter/src/HelixUtils.h b/Phys/DecayTreeFitter/src/lib/HelixUtils.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/HelixUtils.h
rename to Phys/DecayTreeFitter/src/lib/HelixUtils.h
diff --git a/Phys/DecayTreeFitter/src/InteractionPoint.cpp b/Phys/DecayTreeFitter/src/lib/InteractionPoint.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/InteractionPoint.cpp
rename to Phys/DecayTreeFitter/src/lib/InteractionPoint.cpp
diff --git a/Phys/DecayTreeFitter/src/InteractionPoint.h b/Phys/DecayTreeFitter/src/lib/InteractionPoint.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/InteractionPoint.h
rename to Phys/DecayTreeFitter/src/lib/InteractionPoint.h
diff --git a/Phys/DecayTreeFitter/src/InternalParticle.cpp b/Phys/DecayTreeFitter/src/lib/InternalParticle.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/InternalParticle.cpp
rename to Phys/DecayTreeFitter/src/lib/InternalParticle.cpp
diff --git a/Phys/DecayTreeFitter/src/InternalParticle.h b/Phys/DecayTreeFitter/src/lib/InternalParticle.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/InternalParticle.h
rename to Phys/DecayTreeFitter/src/lib/InternalParticle.h
diff --git a/Phys/DecayTreeFitter/src/InternalRecoTrack.cpp b/Phys/DecayTreeFitter/src/lib/InternalRecoTrack.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/InternalRecoTrack.cpp
rename to Phys/DecayTreeFitter/src/lib/InternalRecoTrack.cpp
diff --git a/Phys/DecayTreeFitter/src/InternalRecoTrack.h b/Phys/DecayTreeFitter/src/lib/InternalRecoTrack.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/InternalRecoTrack.h
rename to Phys/DecayTreeFitter/src/lib/InternalRecoTrack.h
diff --git a/Phys/DecayTreeFitter/src/JetMomentum.cpp b/Phys/DecayTreeFitter/src/lib/JetMomentum.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/JetMomentum.cpp
rename to Phys/DecayTreeFitter/src/lib/JetMomentum.cpp
diff --git a/Phys/DecayTreeFitter/src/JetMomentum.h b/Phys/DecayTreeFitter/src/lib/JetMomentum.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/JetMomentum.h
rename to Phys/DecayTreeFitter/src/lib/JetMomentum.h
diff --git a/Phys/DecayTreeFitter/src/KalmanCalculator.cpp b/Phys/DecayTreeFitter/src/lib/KalmanCalculator.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/KalmanCalculator.cpp
rename to Phys/DecayTreeFitter/src/lib/KalmanCalculator.cpp
diff --git a/Phys/DecayTreeFitter/src/KalmanCalculator.h b/Phys/DecayTreeFitter/src/lib/KalmanCalculator.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/KalmanCalculator.h
rename to Phys/DecayTreeFitter/src/lib/KalmanCalculator.h
diff --git a/Phys/DecayTreeFitter/src/MergedConstraint.cpp b/Phys/DecayTreeFitter/src/lib/MergedConstraint.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/MergedConstraint.cpp
rename to Phys/DecayTreeFitter/src/lib/MergedConstraint.cpp
diff --git a/Phys/DecayTreeFitter/src/MergedConstraint.h b/Phys/DecayTreeFitter/src/lib/MergedConstraint.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/MergedConstraint.h
rename to Phys/DecayTreeFitter/src/lib/MergedConstraint.h
diff --git a/Phys/DecayTreeFitter/src/MissingParticle.cpp b/Phys/DecayTreeFitter/src/lib/MissingParticle.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/MissingParticle.cpp
rename to Phys/DecayTreeFitter/src/lib/MissingParticle.cpp
diff --git a/Phys/DecayTreeFitter/src/MissingParticle.h b/Phys/DecayTreeFitter/src/lib/MissingParticle.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/MissingParticle.h
rename to Phys/DecayTreeFitter/src/lib/MissingParticle.h
diff --git a/Phys/DecayTreeFitter/src/ParticleBase.cpp b/Phys/DecayTreeFitter/src/lib/ParticleBase.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/ParticleBase.cpp
rename to Phys/DecayTreeFitter/src/lib/ParticleBase.cpp
diff --git a/Phys/DecayTreeFitter/src/ParticleBase.h b/Phys/DecayTreeFitter/src/lib/ParticleBase.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/ParticleBase.h
rename to Phys/DecayTreeFitter/src/lib/ParticleBase.h
diff --git a/Phys/DecayTreeFitter/src/Projection.h b/Phys/DecayTreeFitter/src/lib/Projection.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/Projection.h
rename to Phys/DecayTreeFitter/src/lib/Projection.h
diff --git a/Phys/DecayTreeFitter/src/RecoComposite.cpp b/Phys/DecayTreeFitter/src/lib/RecoComposite.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoComposite.cpp
rename to Phys/DecayTreeFitter/src/lib/RecoComposite.cpp
diff --git a/Phys/DecayTreeFitter/src/RecoComposite.h b/Phys/DecayTreeFitter/src/lib/RecoComposite.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoComposite.h
rename to Phys/DecayTreeFitter/src/lib/RecoComposite.h
diff --git a/Phys/DecayTreeFitter/src/RecoMergedPi0.cpp b/Phys/DecayTreeFitter/src/lib/RecoMergedPi0.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoMergedPi0.cpp
rename to Phys/DecayTreeFitter/src/lib/RecoMergedPi0.cpp
diff --git a/Phys/DecayTreeFitter/src/RecoMergedPi0.h b/Phys/DecayTreeFitter/src/lib/RecoMergedPi0.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoMergedPi0.h
rename to Phys/DecayTreeFitter/src/lib/RecoMergedPi0.h
diff --git a/Phys/DecayTreeFitter/src/RecoParticle.cpp b/Phys/DecayTreeFitter/src/lib/RecoParticle.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoParticle.cpp
rename to Phys/DecayTreeFitter/src/lib/RecoParticle.cpp
diff --git a/Phys/DecayTreeFitter/src/RecoParticle.h b/Phys/DecayTreeFitter/src/lib/RecoParticle.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoParticle.h
rename to Phys/DecayTreeFitter/src/lib/RecoParticle.h
diff --git a/Phys/DecayTreeFitter/src/RecoPhoton.cpp b/Phys/DecayTreeFitter/src/lib/RecoPhoton.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoPhoton.cpp
rename to Phys/DecayTreeFitter/src/lib/RecoPhoton.cpp
diff --git a/Phys/DecayTreeFitter/src/RecoPhoton.h b/Phys/DecayTreeFitter/src/lib/RecoPhoton.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoPhoton.h
rename to Phys/DecayTreeFitter/src/lib/RecoPhoton.h
diff --git a/Phys/DecayTreeFitter/src/RecoResonance.cpp b/Phys/DecayTreeFitter/src/lib/RecoResonance.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoResonance.cpp
rename to Phys/DecayTreeFitter/src/lib/RecoResonance.cpp
diff --git a/Phys/DecayTreeFitter/src/RecoResonance.h b/Phys/DecayTreeFitter/src/lib/RecoResonance.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoResonance.h
rename to Phys/DecayTreeFitter/src/lib/RecoResonance.h
diff --git a/Phys/DecayTreeFitter/src/RecoTrack.cpp b/Phys/DecayTreeFitter/src/lib/RecoTrack.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoTrack.cpp
rename to Phys/DecayTreeFitter/src/lib/RecoTrack.cpp
diff --git a/Phys/DecayTreeFitter/src/RecoTrack.h b/Phys/DecayTreeFitter/src/lib/RecoTrack.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/RecoTrack.h
rename to Phys/DecayTreeFitter/src/lib/RecoTrack.h
diff --git a/Phys/DecayTreeFitter/src/Resonance.cpp b/Phys/DecayTreeFitter/src/lib/Resonance.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/Resonance.cpp
rename to Phys/DecayTreeFitter/src/lib/Resonance.cpp
diff --git a/Phys/DecayTreeFitter/src/Resonance.h b/Phys/DecayTreeFitter/src/lib/Resonance.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/Resonance.h
rename to Phys/DecayTreeFitter/src/lib/Resonance.h
diff --git a/Phys/DecayTreeFitter/src/VtxErrCode.cpp b/Phys/DecayTreeFitter/src/lib/VtxErrCode.cpp
similarity index 100%
rename from Phys/DecayTreeFitter/src/VtxErrCode.cpp
rename to Phys/DecayTreeFitter/src/lib/VtxErrCode.cpp
diff --git a/Phys/DecayTreeFitter/src/VtxErrCode.h b/Phys/DecayTreeFitter/src/lib/VtxErrCode.h
similarity index 100%
rename from Phys/DecayTreeFitter/src/VtxErrCode.h
rename to Phys/DecayTreeFitter/src/lib/VtxErrCode.h
diff --git a/Phys/LoKiFitters/CMakeLists.txt b/Phys/LoKiFitters/CMakeLists.txt
index 79ce9597ad48705f059a054ed5e3a1f74e6e6b85..a798af6626f12fe1df6d61fd0c4cdb4c455f5052 100644
--- a/Phys/LoKiFitters/CMakeLists.txt
+++ b/Phys/LoKiFitters/CMakeLists.txt
@@ -44,7 +44,7 @@ gaudi_add_module(LoKiFitters
         LHCb::RecEvent
         LHCb::TrackEvent
         Phys::DaVinciInterfacesLib
-        Phys::DecayTreeFitter
+        Phys::DecayTreeFitterLib
         Phys::KalmanFilter
         Phys::LoKiPhysLib
         Rec::TrackInterfacesLib