diff --git a/src/rm/RequestManagerDelete.cc b/src/rm/RequestManagerDelete.cc
index 8f34b0e01b..7d52e6d1d4 100644
--- a/src/rm/RequestManagerDelete.cc
+++ b/src/rm/RequestManagerDelete.cc
@@ -379,6 +379,15 @@ int VirtualNetworkDelete::drop(int oid, PoolObjectSQL * object, string& error_ms
 
 int SecurityGroupDelete::drop(int oid, PoolObjectSQL * object, string& error_msg)
 {
+    if (object->get_oid() == 0)
+    {
+        error_msg = "The default security group (ID 0) cannot be deleted.";
+
+        object->unlock();
+
+        return -1;
+    }
+
     SecurityGroup * sgroup = static_cast<SecurityGroup *>(object);
 
     if ( sgroup->get_vms() > 0 )