diff --git a/src/classes/PFitter.cpp b/src/classes/PFitter.cpp
index 20f92826..7708c25e 100644
--- a/src/classes/PFitter.cpp
+++ b/src/classes/PFitter.cpp
@@ -2944,7 +2944,7 @@ PDoubleVector PFitter::ParamRound(const PDoubleVector &par, const PDoubleVector
   double dval;
   for (unsigned int i=0; i<par.size(); i++) {
     if (err[i] != 0.0) {
-      exp = round(log10(fabs(err[i])))-2;
+      exp = floor(log10(fabs(err[i]))-2);
       dval = round(par[i]*pow(10.0, -exp))/pow(10.0, -exp);
       par_r[i] = dval;
     } else {