Index: trunk/ppImage/src/ppImageParseDetrend.c
===================================================================
--- trunk/ppImage/src/ppImageParseDetrend.c	(revision 9342)
+++ trunk/ppImage/src/ppImageParseDetrend.c	(revision 9857)
@@ -54,4 +54,11 @@
     }
 
+    if (options->doFringe) {
+        bool status = false;
+        pmFPAfileFromArgs (&status, config, "PPIMAGE.FRINGE", "FRINGE");
+        pmFPAfileFromConf (&status, config, "PPIMAGE.FRINGE", input->fpa);
+        if (!status) psAbort ("ppImageParseDetrend", "can't find a fringe image source");
+    }
+
     // the following files are output targets
     // XXX which of these are required?