diff --git a/doc/mirroring.mkd b/doc/mirroring.mkd
index 0e5b2ce..8b50dc7 100644
--- a/doc/mirroring.mkd
+++ b/doc/mirroring.mkd
@@ -132,8 +132,9 @@ and 'gollum' as examples here.
 
     (Remember the "rc" file is NOT mirrored; it is meant to be site-local).
 
-    Note: if `GL_HOSTNAME` is undefined, all mirroring features are disabled
-    on that server, regardless of other settings.
+    Note: if `GL_HOSTNAME` is undefined, you cannot push to repos which have
+    the 'gitolite.mirror.master' config variable set.  (See 'details' section
+    below for more info on this variable).
 
 5.  On each machine, add the keys for all other machines.  For example, on
     frodo you'd run these two commands:
diff --git a/src/gitolite.pm b/src/gitolite.pm
index 8345f32..28b403a 100644
--- a/src/gitolite.pm
+++ b/src/gitolite.pm
@@ -1208,9 +1208,11 @@ sub mirror_listslaves {
     return ( `git config --file $REPO_BASE/$repo.git/config --get gitolite.mirror.slaves` || '' );
 }
 
+# is a redirect ok for this repo from this slave?
 sub mirror_redirectOK {
     my $repo = shift;
-    my $slave = shift || '';
+    my $slave = shift || return 0;
+        # if we don't know who's asking, the answer is "no"
 
     my $gmrOK = `git config --file $REPO_BASE/$repo.git/config --get gitolite.mirror.redirectOK` || '';
     chomp $gmrOK;
diff --git a/src/gl-auth-command b/src/gl-auth-command
index c12d7f5..61b2f5a 100755
--- a/src/gl-auth-command
+++ b/src/gl-auth-command
@@ -140,8 +140,9 @@ $ENV{GL_REPO}=$repo;
 my $aa = ($verb =~ $R_COMMANDS ? 'R' : 'W');
 
 # writes may get redirected under certain conditions
-if ( $GL_HOSTNAME and $aa eq 'W' and mirror_mode($repo) =~ /^slave of (\S+)/ ) {
+if ( $aa eq 'W' and mirror_mode($repo) =~ /^slave of (\S+)/ ) {
     my $master = $1;
+    die "$ABRT GL_HOSTNAME not set; rejecting push to non-local repo\n" unless $GL_HOSTNAME;
     die "$ABRT $GL_HOSTNAME not the master, please push to $master\n" unless mirror_redirectOK($repo, $GL_HOSTNAME);
     print STDERR "$GL_HOSTNAME ==== $user ($repo) ===> $master\n";
     exec("ssh", $master, "USER=$user", "SOC=$ENV{SSH_ORIGINAL_COMMAND}");