diff --git a/BuildUtils.pm b/BuildUtils.pm
index fe3f3e2fd..3e9067bc3 100644
--- a/BuildUtils.pm
+++ b/BuildUtils.pm
@@ -85,13 +85,16 @@ sub write_file {
 }
 
 # Write a helper script and make it executable.  Both builders ship a
-# mklocalrepo.sh beside the packages they publish; a script written without the
-# executable bit is published broken, so the mode is not left to the caller to
-# remember.
+# mklocalrepo.sh beside the packages they publish, and builddebs.pl installs the
+# genesis postscripts the same way; a script written without the executable bit
+# is shipped broken, so the mode is not left to the caller to remember.  It
+# still varies -- the published repo helper is group-writable, the postscripts
+# are not -- so the caller may say, and 0775 is only the default.
 sub write_script {
-    my ($path, $content) = @_;
+    my ($path, $content, $mode) = @_;
+    $mode = 0775 unless defined $mode;
     write_file($path, $content);
-    chmod 0775, $path or die "Cannot chmod $path: $!\n";
+    chmod $mode, $path or die "Cannot chmod $path: $!\n";
     return;
 }
 
diff --git a/builddebs.pl b/builddebs.pl
index c3a7d8637..1868cb98d 100755
--- a/builddebs.pl
+++ b/builddebs.pl
@@ -199,8 +199,7 @@ sub with_prepared_tree {
             $claim->("postscripts/$f");
             my $text = read_file($src);
             $text =~ s/xcat\.genesis\.\Q$f\E/$f/g;
-            write_file($dst, $text);
-            chmod 0755, $dst;
+            write_script($dst, $text, 0755);
         }
     }
     # xCAT-genesis-scripts keeps a control file per architecture.
diff --git a/xCAT-test/unit/build_utils.t b/xCAT-test/unit/build_utils.t
index 1d1a53609..9fe0f6e25 100644
--- a/xCAT-test/unit/build_utils.t
+++ b/xCAT-test/unit/build_utils.t
@@ -373,6 +373,12 @@ isnt( git_revision( git => sub { '' }, read_file => sub { '' } ), '',
     ok( -x $path, 'and is executable, which is the point of writing it this way' );
     is( (stat $path)[2] & 07777, 0775,
         'with the mode both builders published before' );
+
+    # The genesis postscripts builddebs.pl installs are 0755, not 0775, so the
+    # mode has to stay the caller's to choose.
+    my $ps = File::Spec->catfile($dir, 'bmcsetup');
+    BuildUtils::write_script($ps, "#!/bin/sh\n", 0755);
+    is( (stat $ps)[2] & 07777, 0755, 'a caller may ask for a different mode' );
 }
 
 # ---------------------------------------------------------------- sh() --