diff --git a/src/perl/scripts/compare_versions.pl b/src/perl/scripts/compare_versions.pl
index 87602c77dadbbdbf9f52ed88d0b62dc39fdf4654..fd56667e82d67c9237b425cfaaedbcecee58297c 100755
--- a/src/perl/scripts/compare_versions.pl
+++ b/src/perl/scripts/compare_versions.pl
@@ -7,7 +7,8 @@ my $args0 = `tbse echo`;
 chomp $args0;    
 #print "Args 0 $args0\n";
 
-my @executables = defined $ARGV[0] ? @ARGV : ('binary_c-ref','binary_c');
+my @executables = ('binary_c-ref','binary_c');
+my @firstargs = @ARGV;
 my %out;
 threads::shared::share(%out);
 my $n=0;
@@ -30,29 +31,32 @@ while(1)
         );
     %out=();
     my $args = $args0;
-    my $extra;
-    
-    # fix idum
-    $extra .= ' --idum -'.int(65000*rand()).' ';
-
-    # randomize M1, M2, per etc.
-    my $m1 = randval(0.1,100,1);
-    $extra .= " --M_1 $m1 ";
-    $extra .= ' --M_2 '.randval(0.1,$m1,1).' ';
-    $extra .= ' --orbital_period '.randval(0.1,100,1).' --separation 0 ';
-    $extra .= ' --metallicity '.randval(1e-4,0.03,1).' ';
+    my $extra = shift @firstargs;
 
-    # common envelope 
-    my $comenv = rand()>0.5 ? 0 : 1;
-    $extra .= ' --comenv_prescription '.$comenv.' ';
-    $extra .= ' --alpha_ce '.randval(0.0,5.0,0).' ';
-    $extra .= ' --lambda_ce '.(rand()>0.5 ? -1 : randval(0,1,0)).' ';
-    if($comenv == 1)
+    if(!defined $extra)
     {
-        $extra .= ' --nelemans_gamma '.randval(1,2,0).' --nelemans_n_comenvs 1 ';
-    }
-    
-    
+        
+        # fix idum
+        $extra .= ' --idum -'.int(65000*rand()).' ';
+
+        # randomize M1, M2, per etc.
+        my $m1 = randval(0.1,100,1);
+        $extra .= " --M_1 $m1 ";
+        $extra .= ' --M_2 '.randval(0.1,$m1,1).' ';
+        $extra .= ' --orbital_period '.randval(0.1,100,1).' --separation 0 ';
+        $extra .= ' --metallicity '.randval(1e-4,0.03,1).' ';
+
+        # common envelope 
+        my $comenv = rand()>0.5 ? 0 : 1;
+        $extra .= ' --comenv_prescription '.$comenv.' ';
+        $extra .= ' --alpha_ce '.randval(0.0,5.0,0).' ';
+        $extra .= ' --lambda_ce '.(rand()>0.5 ? -1 : randval(0,1,0)).' ';
+        if($comenv == 1)
+        {
+            $extra .= ' --nelemans_gamma '.randval(1,2,0).' --nelemans_n_comenvs 1 ';
+        }
+        
+    }    
     print "$extra\n";
 
     # append extra args
diff --git a/todo-comenv b/todo-comenv
index 1231c21bb4ddf92a406cc3848e82e11b96cfa55f..787810252ea17dc8d4504f53058cf163e48067ed 100644
--- a/todo-comenv
+++ b/todo-comenv
@@ -14,10 +14,11 @@
 
 todo
 
-tm1,tm2
-tn
+
 tscls
 lums
 GB
 
 check all pointers to original vars
+
+./src/perl/scripts/compare_versions.pl " --idum -60345  --M_1 83.8543  --M_2 2.08927  --orbital_period 14.9016 --separation 0  --metallicity 0.000132728  --comenv_prescription 0  --alpha_ce 1.27633  --lambda_ce 0.406764"