diff --git a/src/classes/PFitter.cpp b/src/classes/PFitter.cpp
index 923f39e6..20f92826 100644
--- a/src/classes/PFitter.cpp
+++ b/src/classes/PFitter.cpp
@@ -2943,9 +2943,13 @@ PDoubleVector PFitter::ParamRound(const PDoubleVector &par, const PDoubleVector
   int exp;
   double dval;
   for (unsigned int i=0; i<par.size(); i++) {
-    exp = round(log10(fabs(err[i])))-2;
-    dval = round(par[i]*pow(10.0, -exp))/pow(10.0, -exp);
-    par_r[i] = dval;
+    if (err[i] != 0.0) {
+      exp = round(log10(fabs(err[i])))-2;
+      dval = round(par[i]*pow(10.0, -exp))/pow(10.0, -exp);
+      par_r[i] = dval;
+    } else {
+      par_r[i] = par[i];
+    }
   }
   
   return par_r;