diff --git a/Detectors/PHOS/calib/include/PHOSCalibWorkflow/TurnOnHistos.h b/Detectors/PHOS/calib/include/PHOSCalibWorkflow/TurnOnHistos.h
index 4457da2e100ad..0814fe0da4547 100644
--- a/Detectors/PHOS/calib/include/PHOSCalibWorkflow/TurnOnHistos.h
+++ b/Detectors/PHOS/calib/include/PHOSCalibWorkflow/TurnOnHistos.h
@@ -76,7 +76,7 @@ class TurnOnHistos
   /// \param bitset with channels fired in event
   void fillFiredMap(const std::bitset<NCHANNELS>& bs)
   {
-    for (short i = NCHANNELS; --i;) {
+    for (size_t i = 0; i < NCHANNELS; ++i) {
       if (bs[i]) {
         mGoodMap[i]++;
       }
@@ -87,7 +87,7 @@ class TurnOnHistos
   /// \param bitset with channels fired in event
   void fillNoisyMap(const std::bitset<NCHANNELS>& bs)
   {
-    for (short i = NCHANNELS; --i;) {
+    for (size_t i = 0; i < NCHANNELS; ++i) {
       if (bs[i]) {
         mNoisyMap[i]++;
       }
diff --git a/Detectors/PHOS/calib/src/PHOSRunbyrunCalibrator.cxx b/Detectors/PHOS/calib/src/PHOSRunbyrunCalibrator.cxx
index baa20307b0fbd..63e51f06c0e64 100644
--- a/Detectors/PHOS/calib/src/PHOSRunbyrunCalibrator.cxx
+++ b/Detectors/PHOS/calib/src/PHOSRunbyrunCalibrator.cxx
@@ -127,11 +127,11 @@ bool PHOSRunbyrunSlot::checkCluster(const Cluster& clu)
     return false;
   }
   // First check BadMap
-  float posX, posZ;
+  float posX{0}, posZ{0};
   clu.getLocalPosition(posX, posZ);
-  short absId;
+  short absId{0};
   Geometry::relPosToAbsId(clu.module(), posX, posZ, absId);
-  if (!mBadMap->isChannelGood(absId)) {
+  if (mBadMap && absId >= 0 && !mBadMap->isChannelGood(absId)) {
     return false;
   }
   return (clu.getEnergy() > 0.3 && clu.getMultiplicity() > 1);
diff --git a/Detectors/PHOS/calib/src/PHOSTurnonCalibrator.cxx b/Detectors/PHOS/calib/src/PHOSTurnonCalibrator.cxx
index 5413b20f491b8..432090c280ff8 100644
--- a/Detectors/PHOS/calib/src/PHOSTurnonCalibrator.cxx
+++ b/Detectors/PHOS/calib/src/PHOSTurnonCalibrator.cxx
@@ -36,7 +36,7 @@ PHOSTurnonSlot::PHOSTurnonSlot(bool useCCDB) : mUseCCDB(useCCDB)
 PHOSTurnonSlot::PHOSTurnonSlot(const PHOSTurnonSlot& other)
 {
   mUseCCDB = other.mUseCCDB;
-  mRunStartTime = other.mUseCCDB;
+  mRunStartTime = other.mRunStartTime;
   mFiredTiles.reset();
   mNoisyTiles.reset();
   mTurnOnHistos = std::make_unique<TurnOnHistos>();
@@ -91,15 +91,17 @@ void PHOSTurnonSlot::scanClusters(const gsl::span<const Cell>& cells, const Trig
   for (int i = firstCellInEvent; i < lastCellInEvent; i++) {
     const Cell& c = cells[i];
     if (c.getTRU()) {
-      mNoisyTiles.set(c.getTRUId() - Geometry::getTotalNCells() - 1);
+      auto channel = c.getTRUId() - Geometry::getTotalNCells() - 1;
+      if (channel >= 0) {
+        mNoisyTiles.set(channel);
+      }
     }
   }
 
   // Copy to have good and noisy map
   mFiredTiles.reset();
-  char mod;
-  float x, z;
-  short ddl;
+  float x{0}, z{0};
+  short ddl{0};
   int firstCluInEvent = clutr.getFirstEntry();
   int lastCluInEvent = firstCluInEvent + clutr.getNumberOfObjects();
   for (int i = firstCluInEvent; i < lastCluInEvent; i++) {
@@ -107,7 +109,7 @@ void PHOSTurnonSlot::scanClusters(const gsl::span<const Cell>& cells, const Trig
     if (clu.getEnergy() < 1.e-4) {
       continue;
     }
-    mod = clu.module();
+    char mod = clu.module();
     clu.getLocalPosition(x, z);
     // TODO: do we need separate 2x2 and 4x4 spectra? Switch?
     //  short truId2x2 = Geometry::relPosToTruId(mod, x, z, 0);
@@ -123,7 +125,7 @@ void PHOSTurnonSlot::scanClusters(const gsl::span<const Cell>& cells, const Trig
   // Fill final good and noisy maps
   mTurnOnHistos->fillFiredMap(mFiredTiles);
   mNoisyTiles ^= mFiredTiles;
-  mTurnOnHistos->fillNoisyMap(mFiredTiles);
+  mTurnOnHistos->fillNoisyMap(mNoisyTiles);
 }
 //==============================================