--- loncom/lonnet/perl/lonnet.pm	2003/07/05 10:07:11	1.387
+++ loncom/lonnet/perl/lonnet.pm	2003/07/06 10:30:21	1.388
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.387 2003/07/05 10:07:11 www Exp $
+# $Id: lonnet.pm,v 1.388 2003/07/06 10:30:21 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -2801,13 +2801,16 @@ sub modifyuser {
     } else {
         %names = @tmp;
     }
-
-    if (defined($first))  { $names{'firstname'}  = $first; }
+#
+# Make sure to not trash student environment if instructor does not bother
+# to supply name and email information
+#
+    if ($first)  { $names{'firstname'}  = $first; }
     if (defined($middle)) { $names{'middlename'} = $middle; }
-    if (defined($last))   { $names{'lastname'}   = $last; }
+    if ($last)   { $names{'lastname'}   = $last; }
     if (defined($gene))   { $names{'generation'} = $gene; }
-    if (defined($email))  { $names{'notification'} = $email;
-                            $names{'critnotification'} = $email; }
+    if ($email)  { $names{'notification'} = $email;
+                   $names{'critnotification'} = $email; }
 
     my $reply = &put('environment', \%names, $udom,$uname);
     if ($reply ne 'ok') { return 'error: '.$reply; }