Index: trunk/psModules/src/imcombine/pmSubtractionStamps.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtractionStamps.c	(revision 30824)
+++ trunk/psModules/src/imcombine/pmSubtractionStamps.c	(revision 31023)
@@ -926,5 +926,5 @@
 
     // this is an unrecoverable error : something really bogus in the data
-    if (stamps->normWindow1 == 0) {
+    if (stamps->normWindow1 <= 0) {
         psError(PM_ERR_STAMPS, true, "Unable to determine normalisation window size (1).");
 	psFree (stats);
@@ -935,5 +935,5 @@
         return false;
     }
-    if (stamps->normWindow2 == 0) {
+    if (stamps->normWindow2 <= 0) {
         psError(PM_ERR_STAMPS, true, "Unable to determine normalisation window size (2).");
 	psFree (stats);