diff --git a/math/mathcore/src/TMath.cxx b/math/mathcore/src/TMath.cxx

index 942bb55..72618fc 100644

--- a/math/mathcore/src/TMath.cxx

+++ b/math/mathcore/src/TMath.cxx

@@ -1210,7 +1210,9 @@ void TMath::Quantiles(Int_t n, Int_t nprob, Double_t *x, Double_t *quantiles, Do

          else

             nppm = n*prob[i]; // use m = 0

-         j = TMath::FloorNint(nppm);

+         // be careful with machine precision

+         double eps = 4 * TMath::Limits<Double_t>::Epsilon();

+         j = TMath::FloorNint(nppm + eps);

          // LM : fix for numerical problems if nppm is actually equal to j, but results different for numerical error

          // g in the paper is nppm -j