Index: trunk/psphot/src/psphotSkyReplace.c
===================================================================
--- trunk/psphot/src/psphotSkyReplace.c	(revision 28013)
+++ trunk/psphot/src/psphotSkyReplace.c	(revision 29936)
@@ -5,6 +5,5 @@
     bool status = true;
 
-    int num = psMetadataLookupS32 (&status, config->arguments, "PSPHOT.INPUT.NUM");
-    psAssert (status, "programming error: must define PSPHOT.INPUT.NUM");
+    int num = psphotFileruleCount(config, filerule);
 
     // skip the chisq image (optionally?)