Index: /trunk/psModules/src/camera/pmFPAMosaic.c
===================================================================
--- /trunk/psModules/src/camera/pmFPAMosaic.c	(revision 10516)
+++ /trunk/psModules/src/camera/pmFPAMosaic.c	(revision 10517)
@@ -1053,7 +1053,10 @@
     targetHDU->header = psMetadataCopy(targetHDU->header, sourceHDU->header);
     pmHDU *phu = pmHDUGetHighest(target->parent, target, NULL);
-    if (!phu || !phu->header) {
+    if (!phu) {
         psError(PS_ERR_UNKNOWN, true, "Unable to find HDU after mosaicking.\n");
         return false;
+    }
+    if (!phu->header) {
+        phu->header = psMetadataAlloc();
     }
     if (!pmConfigConformHeader(phu->header, phu->format)) {