--- loncom/interface/loncommon.pm	2008/08/28 03:04:41	1.675
+++ loncom/interface/loncommon.pm	2008/09/01 17:58:29	1.676
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # a pile of common routines
 #
-# $Id: loncommon.pm,v 1.675 2008/08/28 03:04:41 raeburn Exp $
+# $Id: loncommon.pm,v 1.676 2008/09/01 17:58:29 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -9380,9 +9380,11 @@ sub init_user_environment {
 
 sub _add_to_env {
     my ($idf,$env_data,$prefix) = @_;
-    while (my ($key,$value) = each(%$env_data)) {
-	$idf->{$prefix.$key} = $value;
-	$env{$prefix.$key}   = $value;
+    if (ref($env_data) eq 'HASH') {
+        while (my ($key,$value) = each(%$env_data)) {
+	    $idf->{$prefix.$key} = $value;
+	    $env{$prefix.$key}   = $value;
+        }
     }
 }