diff --git a/interface/FastTemplate.h b/interface/FastTemplate.h
index 08e7279aa0d..b61be41a120 100644
--- a/interface/FastTemplate.h
+++ b/interface/FastTemplate.h
@@ -120,7 +120,10 @@ template <typename T> class FastTemplate_t {
           }
           return *this;
         }
-        virtual FastTemplate_t<T> & operator=(const TH1 &other) {
+        virtual FastTemplate_t & operator=(const TH1 &other) {
+          if(other.GetDimension() != 1) {
+             throw std::invalid_argument("FastTemplate_t assignment error: right hand histogram must be 1-dimensional");
+          }
           if ((int)size() != other.GetNbinsX()) {
             size_ = (unsigned int)other.GetNbinsX();
             values_.resize(size_);
@@ -200,7 +203,7 @@ template <typename T, typename U=Double_t> class FastHisto_t : public FastTempla
           else this->CopyValues(other);
           return *this;
         }
-        ~FastHisto_t<T,U>(){}
+        ~FastHisto_t(){}
 };
 template <typename T, typename U=Double_t> class FastHisto2D_t : public FastTemplate_t<T> {
 private:
@@ -278,9 +281,12 @@ template <typename T, typename U=Double_t> class FastHisto2D_t : public FastTemp
           else this->CopyValues(other);
           return *this;
         }
-        FastHisto2D_t<T,U>& operator=(const TH2 &other) {
-          if (GetNbinsX() != other.GetNbinsX() || GetNbinsY() != other.GetNbinsY()) {
-            FastHisto2D_t<T,U> fh(other);
+        FastHisto2D_t& operator=(const TH1 &other) {
+          if(other.GetDimension() != 2) {
+             throw std::invalid_argument("FastHisto2D_t assignment error: right hand histogram must be 2-dimensional");
+          }
+          if (int(GetNbinsX()) != other.GetNbinsX() || int(GetNbinsY()) != other.GetNbinsY()) {
+            FastHisto2D_t<T,U> fh(static_cast<TH2 const&>(other));
             swap(fh);
           }
           else this->CopyValues(other);
@@ -374,9 +380,12 @@ template <typename T, typename U=Double_t> class FastHisto3D_t : public FastTemp
           else this->CopyValues(other);
           return *this;
         }
-        FastHisto3D_t<T,U>& operator=(const TH3 &other) {
-          if (GetNbinsX() != other.GetNbinsX() || GetNbinsY() != other.GetNbinsY() || GetNbinsZ() != other.GetNbinsZ()) {
-            FastHisto3D_t<T,U> fh(other);
+        FastHisto3D_t<T,U>& operator=(const TH1 &other) {
+          if(other.GetDimension() != 3) {
+             throw std::invalid_argument("FastHisto3D_t assignment error: right hand histogram must be 3-dimensional");
+          }
+          if (int(GetNbinsX()) != other.GetNbinsX() || int(GetNbinsY()) != other.GetNbinsY() || int(GetNbinsZ()) != other.GetNbinsZ()) {
+            FastHisto3D_t<T,U> fh(static_cast<TH3 const&>(other));
             swap(fh);
           }
           else this->CopyValues(other);
diff --git a/src/HZZ4LRooPdfs.cc b/src/HZZ4LRooPdfs.cc
index 9e221d4c141..613031da83b 100644
--- a/src/HZZ4LRooPdfs.cc
+++ b/src/HZZ4LRooPdfs.cc
@@ -4009,11 +4009,14 @@ ClassImp(RooCPSHighMassGGH)
      beta = getBeta(mH,effKPrime);
    }
 
+   // Cast the "x" proxy to double only once to avoid overhead and ambiguous
+   // overloads the TComplex operators.
+   const double xVal = x;
 
-   Double_t bwHM = x / ( TMath::Power( TMath::Power(x,2) - TMath::Power(mH+delta,2) , 2 ) + TMath::Power(x,2)*TMath::Power(effKPrime*width,2) ); 
+   Double_t bwHM = xVal / ( TMath::Power( TMath::Power(xVal,2) - TMath::Power(mH+delta,2) , 2 ) + TMath::Power(xVal,2)*TMath::Power(effKPrime*width,2) ); 
 
    Double_t splineFactor;
-   if (x<1850) splineFactor = Spline(x);
+   if (xVal<1850) splineFactor = Spline(xVal);
    else splineFactor = Spline(1850);
 
    Double_t signal = bwHM*splineFactor;
@@ -4024,9 +4027,9 @@ ClassImp(RooCPSHighMassGGH)
    TComplex M = MSquared.Sqrt(MSquared);
    TComplex Exp1 = MSquared.Exp((TComplex)alpha);
    TComplex Exp2 = MSquared.Exp(-(TComplex)alpha);
-   TComplex Exp3 = MSquared.Exp(-x*(TComplex)alpha/M);
+   TComplex Exp3 = MSquared.Exp(-xVal*(TComplex)alpha/M);
 
-   double interference = -r*(1-TMath::Exp(-beta*(x-150.)/mH_eff))*((Exp1/(x-M)-Exp2/(x+M))*Exp3).Re();
+   double interference = -r*(1-TMath::Exp(-beta*(xVal-150.)/mH_eff))*((Exp1/(xVal-M)-Exp2/(xVal+M))*Exp3).Re();
 
    Double_t fValue = signal + IntStr*interference/( TMath::Sqrt(1-BRnew) );
    if (fValue > 0) return fValue;
@@ -4655,7 +4658,11 @@ ClassImp(RooBWHighMassGGH)
    Double_t r = getR(mH,effKPrime);
    Double_t beta = getBeta(mH,effKPrime);
 
-   Double_t bwHM = x / ( TMath::Power( TMath::Power(x,2) - TMath::Power(mH+delta,2) , 2 ) + TMath::Power(x,2)*TMath::Power(effKPrime*width,2) ); 
+   // Cast the "x" proxy to double only once to avoid overhead and ambiguous
+   // overloads the TComplex operators.
+   const double xVal = x;
+
+   Double_t bwHM = xVal / ( TMath::Power( TMath::Power(xVal,2) - TMath::Power(mH+delta,2) , 2 ) + TMath::Power(xVal,2)*TMath::Power(effKPrime*width,2) ); 
    Double_t signal = bwHM;
      
    Double_t k=0.25;
@@ -4666,7 +4673,7 @@ ClassImp(RooBWHighMassGGH)
    TComplex Exp2 = MSquared.Exp(-(TComplex)alpha);
    TComplex Exp3 = MSquared.Exp(-x*(TComplex)alpha/M);
 
-   double interference = -r*(1-TMath::Exp(-beta*(x-150.)/mH_eff))*((Exp1/(x-M)-Exp2/(x+M))*Exp3).Re();
+   double interference = -r*(1-TMath::Exp(-beta*(xVal-150.)/mH_eff))*((Exp1/(xVal-M)-Exp2/(xVal+M))*Exp3).Re();
 
    Double_t fValue = signal + IntStr*interference/( TMath::Sqrt(1-BRnew) );
    if (fValue > 0) return fValue;
@@ -6552,11 +6559,14 @@ ClassImp(RooCPSHighMassVBF)
      beta = getBeta(mH,effKPrime);
    }
 
+   // Cast the "x" proxy to double only once to avoid overhead and ambiguous
+   // overloads the TComplex operators.
+   const double xVal = x;
 
-   Double_t bwHM = x / ( TMath::Power( TMath::Power(x,2) - TMath::Power(mH+delta,2) , 2 ) + TMath::Power(x,2)*TMath::Power(effKPrime*width,2) ); 
+   Double_t bwHM = xVal / ( TMath::Power( TMath::Power(xVal,2) - TMath::Power(mH+delta,2) , 2 ) + TMath::Power(xVal,2)*TMath::Power(effKPrime*width,2) ); 
 
    Double_t splineFactor;
-   if (x<1850) splineFactor = Spline(x);
+   if (xVal<1850) splineFactor = Spline(xVal);
    else splineFactor = Spline(1850);
 
    Double_t signal = bwHM*splineFactor;
@@ -6567,9 +6577,9 @@ ClassImp(RooCPSHighMassVBF)
    TComplex M = MSquared.Sqrt(MSquared);
    TComplex Exp1 = MSquared.Exp((TComplex)alpha);
    TComplex Exp2 = MSquared.Exp(-(TComplex)alpha);
-   TComplex Exp3 = MSquared.Exp(-x*(TComplex)alpha/M);
+   TComplex Exp3 = MSquared.Exp(-xVal*(TComplex)alpha/M);
 
-   double interference = -r*(1-TMath::Exp(-beta*(x-150.)/mH_eff))*((Exp1/(x-M)-Exp2/(x+M))*Exp3).Re();
+   double interference = -r*(1-TMath::Exp(-beta*(xVal-150.)/mH_eff))*((Exp1/(xVal-M)-Exp2/(xVal+M))*Exp3).Re();
 
    Double_t fValue = signal*(1+IntStr*interference/(bwHM*( TMath::Sqrt(1-BRnew) ))); 
    if (fValue > 0) return fValue;
@@ -7645,13 +7655,16 @@ ClassImp(RooSigPlusInt)
 
  Double_t RooSigPlusInt::evaluate() const 
  { 
+   // Cast the "x" proxy to double only once to avoid overhead and ambiguous
+   // overloads the TComplex operators.
+   const double xVal = x;
 
    Double_t totWidthSF = CSquared/(1-BRnew);
 
    Double_t mH_eff = mH*TMath::Sqrt(1-k*(totWidthSF*width/mH)*(totWidthSF*width/mH));
-
+ 
    Double_t splineFactor = Spline(x);
-   Double_t bwHM = x / ( TMath::Power( TMath::Power(x,2) - TMath::Power(mH+delta,2) , 2 ) + TMath::Power(x,2)*TMath::Power(totWidthSF*width,2) ); 
+   Double_t bwHM = xVal / ( TMath::Power( TMath::Power(xVal,2) - TMath::Power(mH+delta,2) , 2 ) + TMath::Power(xVal,2)*TMath::Power(totWidthSF*width,2) ); 
 
    Double_t signal = splineFactor*bwHM;
       
@@ -7659,9 +7672,9 @@ ClassImp(RooSigPlusInt)
    TComplex M = MSquared.Sqrt(MSquared);
    TComplex Exp1 = MSquared.Exp((TComplex)alpha);
    TComplex Exp2 = MSquared.Exp(-(TComplex)alpha);
-   TComplex Exp3 = MSquared.Exp(-x*(TComplex)alpha/M);
+   TComplex Exp3 = MSquared.Exp(-xVal*(TComplex)alpha/M);
 
-   double interference = -r*sqrt(1/1-BRnew)*(1-TMath::Exp(-beta*(x-150.)/mH_eff))*((Exp1/(x-M)-Exp2/(x+M))*Exp3).Re();
+   double interference = -r*sqrt(1/1-BRnew)*(1-TMath::Exp(-beta*(xVal-150.)/mH_eff))*((Exp1/(xVal-M)-Exp2/(xVal+M))*Exp3).Re();
 
    return signal + interference;   
    
diff --git a/src/ProfiledLikelihoodRatioTestStat.cc b/src/ProfiledLikelihoodRatioTestStat.cc
index 7bbea842df5..3a29700de56 100644
--- a/src/ProfiledLikelihoodRatioTestStat.cc
+++ b/src/ProfiledLikelihoodRatioTestStat.cc
@@ -1,6 +1,7 @@
 #include "../interface/ProfiledLikelihoodRatioTestStat.h"
 #include "../interface/CloseCoutSentry.h"
 #include <stdexcept>
+#include <RooFitResult.h>
 #include <RooRealVar.h>
 
 Double_t ProfiledLikelihoodRatioTestStat::Evaluate(RooAbsData& data, RooArgSet& nullPOI)