diff --git a/Netdisco/Changes b/Netdisco/Changes
index 0f99ffd3..a5daeaae 100644
--- a/Netdisco/Changes
+++ b/Netdisco/Changes
@@ -27,6 +27,7 @@
   * Buttons for discover/macsuck/arpnip on device details page
   * Support 'path' config option as alternative to --path /mountpoint
   * Local plugins can be placed in ${NETDISCO_HOME}/site_plugins/...
+  * Missing mibdirs causes all MIBs to be loaded (with a warning)
 
   [BUG FIXES]
 
diff --git a/Netdisco/lib/App/Netdisco/Util/SNMP.pm b/Netdisco/lib/App/Netdisco/Util/SNMP.pm
index e7f1964b..a2703288 100644
--- a/Netdisco/lib/App/Netdisco/Util/SNMP.pm
+++ b/Netdisco/lib/App/Netdisco/Util/SNMP.pm
@@ -149,7 +149,14 @@ sub _try_connect {
 sub _build_mibdirs {
   my $home = (setting('mibhome') || $ENV{NETDISCO_HOME} || $ENV{HOME});
   return map { dir($home, $_) }
-             @{ setting('mibdirs') || [] };
+             @{ setting('mibdirs') || _get_mibdirs_content($home) };
+}
+
+sub _get_mibdirs_content {
+  my $home = shift;
+  warning 'Netdisco SNMP work will be really slow - loading ALL MIBs. Please set mibdirs.';
+  my @list = map {s|$home/||; $_} grep {-d} glob("$home/*");
+  return \@list;
 }
 
 =head2 snmp_comm_reindex( $snmp, $vlan )