Index: trunk/psModules/src/imcombine/pmReadoutCombine.c
===================================================================
--- trunk/psModules/src/imcombine/pmReadoutCombine.c	(revision 16861)
+++ trunk/psModules/src/imcombine/pmReadoutCombine.c	(revision 16906)
@@ -313,7 +313,5 @@
             } else {
                 outputImage[yOut][xOut] = psStatsGetValue(stats, params->combine);
-                if (!isfinite(outputImage[yOut][xOut])) {
-                    outputMask[yOut][xOut] = params->blank;
-                }
+                outputMask[yOut][xOut] = isfinite(outputImage[yOut][xOut]) ? 0 : params->blank;
                 if (params->weights) {
                     float stdev = psStatsGetValue(stats, combineStdev);