Index: trunk/psModules/src/detrend/pmDark.c
===================================================================
--- trunk/psModules/src/detrend/pmDark.c	(revision 24819)
+++ trunk/psModules/src/detrend/pmDark.c	(revision 24869)
@@ -978,5 +978,5 @@
 	      // a NULL rule means 'use the name as the single concept'
               const char *rule = psMetadataLookupStr(&mdok, row, PM_DARK_FITS_RULE);
-	      if (!strcasecmp(rule, "NONE")) {
+	      if (!rule || !strcasecmp(rule, "NONE")) {
 		  ord->rule = NULL;
 	      } else {