Index: trunk/psModules/src/imcombine/pmSubtraction.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtraction.c	(revision 20832)
+++ trunk/psModules/src/imcombine/pmSubtraction.c	(revision 20838)
@@ -1319,4 +1319,6 @@
         psThreadJob *job;               // Completed job
         while ((job = psThreadJobGetDone())) {
+            psAssert(strcmp(job->type, "PSMODULES_SUBTRACTION_CONVOLVE") == 0,
+                     "Job has incorrect type: %s", job->type);
             psFree(job);
         }