Index: /trunk/ppSub/src/ppSubMatchPSFs.c
===================================================================
--- /trunk/ppSub/src/ppSubMatchPSFs.c	(revision 25117)
+++ /trunk/ppSub/src/ppSubMatchPSFs.c	(revision 25118)
@@ -260,6 +260,10 @@
     pmConceptsCopyFPA(refConv->parent->parent->parent, refRO->parent->parent->parent, true, true);
 
-    psImageCovarianceTransfer(inConv->variance, inConv->covariance);
-    psImageCovarianceTransfer(refConv->variance, refConv->covariance);
+    if (inConv->variance) {
+        psImageCovarianceTransfer(inConv->variance, inConv->covariance);
+    }
+    if (refConv->variance) {
+        psImageCovarianceTransfer(refConv->variance, refConv->covariance);
+    }
 
     return true;