diff --git a/plugins/senderbase/senderbase b/plugins/senderbase/senderbase
index 77a55bad..921c056f 100755
--- a/plugins/senderbase/senderbase
+++ b/plugins/senderbase/senderbase
@@ -16,9 +16,11 @@ track their current reputation score.
 
 =head1 CONFIGURATION
 
-By default, the script will use the first IP address returned by C<hostname -I>.
-If that's not the right address to use, set the C<ip_address> environment
-variable to the appropriate value.
+By default, the script will use the first IP address returned by
+C<hostname -I>.  If that's not the right address to use, set the
+C<ip_address> environment variable to the appropriate value.  (Note that
+if a host has multiple IP addresses, there's no guaranteed ordering for
+C<hostname -I>, so you should set the address explicitly in that case.)
 
  [senderbase]
    env.ip_address 8.8.8.8
@@ -40,7 +42,7 @@ This plugin is made available under a CC0 waiver:
 
 =cut
 
-real_ip_address=${ip_address:-$(hostname -I | head -1)}
+real_ip_address=${ip_address:-$(hostname -I | awk '{print $1}')}
 ip_reversed=$(echo $real_ip_address | sed -re 's/^([0-9]+)\.([0-9]+)\.([0-9]+)\.([0-9]+)$/\4.\3.\2.\1/')
 query_host=${ip_reversed}.rf.senderbase.org