Index: trunk/psModules/src/detrend/pmShifts.c
===================================================================
--- trunk/psModules/src/detrend/pmShifts.c	(revision 14332)
+++ trunk/psModules/src/detrend/pmShifts.c	(revision 15322)
@@ -467,12 +467,9 @@
     // Purposely ignoring the weight map --- don't care about the weight map for a detrend image
 
-    if (maskVal && detrend->mask) {
-        psImage *convolved = psImageConvolveMask(detrend->mask, maskVal, kernel);
-        if (!convolved) {
-            psError(PS_ERR_UNKNOWN, false, "Unable to convolve detrend mask.");
-            return false;
-        }
-        psFree(detrend->mask);
-        detrend->mask = convolved;
+    if (maskVal && detrend->mask && !psImageConvolveMaskDirect(detrend->mask, detrend->mask, maskVal, 0,
+                                                               kernel->xMin, kernel->xMax,
+                                                               kernel->yMin, kernel->yMax)) {
+        psError(PS_ERR_UNKNOWN, false, "Unable to convolve detrend mask.");
+        return false;
     }