Index: trunk/psModules/src/imcombine/pmSubtractionMatch.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtractionMatch.c	(revision 16479)
+++ trunk/psModules/src/imcombine/pmSubtractionMatch.c	(revision 16604)
@@ -434,5 +434,6 @@
 
             psTrace("psModules.imcombine", 2, "Convolving...\n");
-            if (!pmSubtractionConvolve(conv1, conv2, ro1, ro2, subMask, maskBlank, region, kernels, useFFT)) {
+            if (!pmSubtractionConvolve(conv1, conv2, ro1, ro2, subMask, maskBlank, region, kernels,
+                                       true, useFFT)) {
                 psError(PS_ERR_UNKNOWN, false, "Unable to convolve image.");
                 goto MATCH_ERROR;