diff --git a/geant4/PQt_musrSim/QmuSRSim.ui.h b/geant4/PQt_musrSim/QmuSRSim.ui.h
index d74cbc8..482ee05 100644
--- a/geant4/PQt_musrSim/QmuSRSim.ui.h
+++ b/geant4/PQt_musrSim/QmuSRSim.ui.h
@@ -296,6 +296,7 @@ void QmuSRSim::CheckSim()
     my $Geant4PATH= Geant4->text();
     my $SaveDataPATH= SaveData->text();
     my $ROOTSYSPATH=ROOTSYS->text();
+    my $MAC=MAC->text();
     
 # Check if any of them is empty or does not exist
     unless (-d $musrSimPATH) {
@@ -315,6 +316,12 @@ void QmuSRSim::CheckSim()
 	$answ=0;
 	$answtext=$answtext."ROOTSYS Path is wrong!\n";
     }
+
+    my $NewFile="$musrSim/run/$MAC.mac";
+    unless (-e $NewFile) {
+      $answ=0;
+      $answtext=}answtext."Macro file $NewFile exists!\n";
+    }
     
     if ($answ==0) {
 	print STDERR $answtext;