Index: trunk/ippTasks/detrend.stack.pro
===================================================================
--- trunk/ippTasks/detrend.stack.pro	(revision 12369)
+++ trunk/ippTasks/detrend.stack.pro	(revision 12370)
@@ -134,5 +134,5 @@
     end
 
-    if ($WORKDIR == NULL)
+    if ("$WORKDIR" == "NULL")
       $outroot = `pwd`
     else
@@ -149,5 +149,5 @@
 
     $run = detrend_stack.pl --det_id $DET_ID --iteration $ITERATION --class_id $CLASS_ID --det_type $DET_TYPE --camera $CAMERA $ARGS
-    if ($WORKDIR != NULL)
+    if ("$WORKDIR" != "NULL")
       $run = $run --workdir $outroot
     end