Index: trunk/psModules/src/imcombine/pmPSFEnvelope.c
===================================================================
--- trunk/psModules/src/imcombine/pmPSFEnvelope.c	(revision 23189)
+++ trunk/psModules/src/imcombine/pmPSFEnvelope.c	(revision 23191)
@@ -115,4 +115,7 @@
     for (int i = 0; i < inputs->n; i++) {
         pmPSF *psf = inputs->data[i];   // PSF of interest
+        if (!psf) {
+            continue;
+        }
         pmResiduals *resid = psf->residuals;// PSF residuals
         psf->residuals = NULL;