diff --git a/v2.5/toolkit/fastnlotoolkit/fastNLOInterpolBase.cc b/v2.5/toolkit/fastnlotoolkit/fastNLOInterpolBase.cc
index 9a593a0bc6e7d2aea6ea59ccf4a04db4110aa5db..2e8608f673d1d7c0cbbbad91df8d927060ce8872 100644
--- a/v2.5/toolkit/fastnlotoolkit/fastNLOInterpolBase.cc
+++ b/v2.5/toolkit/fastnlotoolkit/fastNLOInterpolBase.cc
@@ -384,7 +384,7 @@ bool fastNLOInterpolBase::CheckX(double& x) {
       return true;
    }
    //printf("x=%e, %e;   fgrid=%e, %e;  ratio: %e\n",x,x-1.,fgrid[0],fgrid[0]-1,x/fgrid[0]-1);
-   if ( x < fgrid[0] && false) {
+   if ( x < fgrid[0] && !fExtendLow) {
       if ( x!=fLastVal[1] && fgrid[0]/x-1>1.e-6)
          warn["CheckX"]<<"Value "<<x<<" is smaller than smallest node (min="<<fgrid[0]<<"). Using this first node."<<endl;
       fLastVal[1] = x; // use this to monitor whenever there was an incident