Index: trunk/psphot/src/psphotSubtractBackground.c
===================================================================
--- trunk/psphot/src/psphotSubtractBackground.c	(revision 34528)
+++ trunk/psphot/src/psphotSubtractBackground.c	(revision 38039)
@@ -29,5 +29,5 @@
     // user-defined masks to test for good/bad pixels (build from recipe list if not yet set)
     psImageMaskType maskVal = psMetadataLookupImageMask(&status, recipe, "MASK.PSPHOT"); // Mask value for bad pixels
-    assert (maskVal);
+    psAssert (maskVal, "MASK.PSPHOT missing from recipe");
 
     psImageBinning *binning = psMetadataLookupPtr(&status, model->analysis, "PSPHOT.BACKGROUND.BINNING");