--- /opt/local/bin/port	2009-09-28 16:42:21.000000000 -0500
+++ port	2009-10-18 03:03:28.000000000 -0500
@@ -437,11 +437,15 @@
             set size [term_get_size stdout]
 
             if {![info exists env(LINES)]} {
-                set env(LINES) [lindex $size 0]
+                if {[lindex $size 0]} {
+                  set env(LINES) [lindex $size 0]
+                }
             }
 
             if {![info exists env(COLUMNS)]} {
-                set env(COLUMNS) [lindex $size 1]
+                if {[lindex $size 1]} {
+                  set env(COLUMNS) [lindex $size 1]
+                }
             }
         }
     }