diff --git a/Detectors/TPC/workflow/include/TPCWorkflow/ClusterSharingMapSpec.h b/Detectors/TPC/workflow/include/TPCWorkflow/ClusterSharingMapSpec.h
index 1bade0eec9c4d..d1fb51c50c4e5 100644
--- a/Detectors/TPC/workflow/include/TPCWorkflow/ClusterSharingMapSpec.h
+++ b/Detectors/TPC/workflow/include/TPCWorkflow/ClusterSharingMapSpec.h
@@ -18,6 +18,7 @@
 
 #include "Framework/DataProcessorSpec.h"
 #include "Framework/Task.h"
+#include "Framework/CCDBParamSpec.h"
 
 namespace o2
 {
@@ -39,6 +40,7 @@ o2::framework::DataProcessorSpec getClusterSharingMapSpec()
   inputs.emplace_back("trackTPC", "TPC", "TRACKS", 0, o2::framework::Lifetime::Timeframe);
   inputs.emplace_back("trackTPCClRefs", "TPC", "CLUSREFS", 0, o2::framework::Lifetime::Timeframe);
   inputs.emplace_back("clusTPC", o2::framework::ConcreteDataTypeMatcher{"TPC", "CLUSTERNATIVE"}, o2::framework::Lifetime::Timeframe);
+  inputs.emplace_back("grpecs", "GLO", "GRPECS", 0, o2::framework::Lifetime::Condition, o2::framework::ccdbParamSpec("GLO/Config/GRPECS", true));
   outputs.emplace_back("TPC", "CLSHAREDMAP", 0, o2::framework::Lifetime::Timeframe);
 
   return o2::framework::DataProcessorSpec{
diff --git a/Detectors/TPC/workflow/src/ClusterSharingMapSpec.cxx b/Detectors/TPC/workflow/src/ClusterSharingMapSpec.cxx
index 7b8259aa70377..d0e5aa121b543 100644
--- a/Detectors/TPC/workflow/src/ClusterSharingMapSpec.cxx
+++ b/Detectors/TPC/workflow/src/ClusterSharingMapSpec.cxx
@@ -20,6 +20,7 @@
 #include "DataFormatsTPC/TrackTPC.h"
 #include "GPUO2InterfaceRefit.h"
 #include "TPCWorkflow/ClusterSharingMapSpec.h"
+#include "DataFormatsParameters/GRPECSObject.h"
 
 using namespace o2::framework;
 using namespace o2::tpc;
@@ -27,10 +28,15 @@ using namespace o2::tpc;
 void ClusterSharingMapSpec::run(ProcessingContext& pc)
 {
   TStopwatch timer;
-
+  static int nHBPerTF = 0;
   const auto tracksTPC = pc.inputs().get<gsl::span<o2::tpc::TrackTPC>>("trackTPC");
   const auto tracksTPCClRefs = pc.inputs().get<gsl::span<o2::tpc::TPCClRefElem>>("trackTPCClRefs");
   const auto& clustersTPC = getWorkflowTPCInput(pc);
+  if (pc.services().get<o2::framework::TimingInfo>().globalRunNumberChanged) { // new run is starting
+    auto grp = pc.inputs().get<o2::parameters::GRPECSObject*>("grpecs");
+    nHBPerTF = grp->getNHBFPerTF();
+    LOGP(info, "Will use {} HB per TF from GRPECS", nHBPerTF);
+  }
 
   auto& bufVec = pc.outputs().make<std::vector<unsigned char>>(Output{o2::header::gDataOriginTPC, "CLSHAREDMAP", 0}, clustersTPC->clusterIndex.nClustersTotal);
   o2::gpu::GPUO2InterfaceRefit::fillSharedClustersMap(&clustersTPC->clusterIndex, tracksTPC, tracksTPCClRefs.data(), bufVec.data());