Index: /trunk/psphot/src/psphotSourceFits.c
===================================================================
--- /trunk/psphot/src/psphotSourceFits.c	(revision 11313)
+++ /trunk/psphot/src/psphotSourceFits.c	(revision 11314)
@@ -365,4 +365,6 @@
     // use the source moments, etc to guess basic model parameters
     pmModel *EXT = pmSourceModelGuess (source, modelTypeEXT);
+    assert (EXT != NULL);
+	
     // if (isnan(EXT->params->data.F32[1])) psAbort ("psphot", "nan in ext fit");