diff --git a/lib/App/Netdisco/Util/SNMP.pm b/lib/App/Netdisco/Util/SNMP.pm
index 2527ab38..0fad3d7f 100644
--- a/lib/App/Netdisco/Util/SNMP.pm
+++ b/lib/App/Netdisco/Util/SNMP.pm
@@ -172,6 +172,7 @@ sub snmp_comm_reindex {
   if ($ver == 3) {
       my $prefix = '';
       my @comms = _build_communities($device, 'read');
+      # find a context prefix configured by the user
       foreach my $c (@comms) {
           next unless $c->{tag}
             and $c->{tag} eq (eval { $device->community->snmp_auth_tag_read } || '');
@@ -182,14 +183,16 @@ sub snmp_comm_reindex {
       debug
         sprintf '[%s] reindexing to "%s%s" (ver: %s, class: %s)',
         $device->ip, $prefix, $vlan, $ver, $snmp->class;
-      $snmp->update(Context => ($prefix . $vlan));
+      $vlan ? $snmp->update(Context => ($prefix . $vlan))
+            : $snmp->update(Context => '');
   }
   else {
       my $comm = $snmp->snmp_comm;
 
       debug sprintf '[%s] reindexing to vlan %s (ver: %s, class: %s)',
         $device->ip, $vlan, $ver, $snmp->class;
-      $snmp->update(Community => $comm . '@' . $vlan);
+      $vlan ? $snmp->update(Community => $comm . '@' . $vlan)
+            : $snmp->update(Community => $comm);
   }
 }
 
diff --git a/lib/App/Netdisco/Worker/Plugin/Macsuck/Nodes.pm b/lib/App/Netdisco/Worker/Plugin/Macsuck/Nodes.pm
index 836fcd80..3f73ca27 100644
--- a/lib/App/Netdisco/Worker/Plugin/Macsuck/Nodes.pm
+++ b/lib/App/Netdisco/Worker/Plugin/Macsuck/Nodes.pm
@@ -27,9 +27,6 @@ register_worker({ stage => 'check', driver => 'snmp' }, sub {
   my $now = 'to_timestamp('. (join '.', gettimeofday) .')';
   my $total_nodes = 0;
 
-  # do this before we start messing with the snmp community string
-  my $guard = guard { }; # FIXME TODO reset snmp community
-
   # cache the device ports to save hitting the database for many single rows
   my $device_ports = {map {($_->port => $_)}
                           $device->ports(undef, {prefetch => {neighbor_alias => 'device'}})->all};
@@ -41,10 +38,14 @@ register_worker({ stage => 'check', driver => 'snmp' }, sub {
 
   # ...then per-vlan if supported
   my @vlan_list = get_vlan_list($device);
-  foreach my $vlan (@vlan_list) {
-    snmp_comm_reindex($snmp, $device, $vlan);
-    my $pv_fwtable = walk_fwtable($device, $interfaces, $port_macs, $device_ports, $vlan);
-    $fwtable = {%$fwtable, %$pv_fwtable};
+  {
+    my $guard = guard { snmp_comm_reindex($snmp, $device, 0) };
+    foreach my $vlan (@vlan_list) {
+      snmp_comm_reindex($snmp, $device, $vlan);
+      my $pv_fwtable =
+        walk_fwtable($device, $interfaces, $port_macs, $device_ports, $vlan);
+      $fwtable = {%$fwtable, %$pv_fwtable};
+    }
   }
 
   # now it's time to call store_node for every node discovered