Index: trunk/psModules/src/imcombine/pmSubtractionMatch.c
===================================================================
--- trunk/psModules/src/imcombine/pmSubtractionMatch.c	(revision 15305)
+++ trunk/psModules/src/imcombine/pmSubtractionMatch.c	(revision 15325)
@@ -15,4 +15,7 @@
 #include "pmSubtraction.h"
 #include "pmSubtractionMatch.h"
+
+
+static bool useFFT = true;              // Do convolutions using FFT
 
 
@@ -223,6 +226,6 @@
     memCheck("start");
 
-    subMask = pmSubtractionMask(reference->mask, inMask, maskBad, size, footprint, badFrac);
-    if (subMask) {
+    subMask = pmSubtractionMask(reference->mask, inMask, maskBad, size, footprint, badFrac, useFFT);
+    if (!subMask) {
         psError(PS_ERR_UNKNOWN, false, "Unable to generate subtraction mask.");
         return false;
@@ -417,5 +420,5 @@
             if (!pmSubtractionConvolve(&convolved->image, &convolved->weight, &convolved->mask,
                                        reference->image, reference->weight, subMask, maskBlank, region,
-                                       solution, kernels, true)) {
+                                       solution, kernels, useFFT)) {
                 psError(PS_ERR_UNKNOWN, false, "Unable to convolve reference image.");
                 goto ERROR;