Index: trunk/ppStack/src/ppStackReadout.c
===================================================================
--- trunk/ppStack/src/ppStackReadout.c	(revision 19532)
+++ trunk/ppStack/src/ppStackReadout.c	(revision 20497)
@@ -96,4 +96,5 @@
     int iter = psMetadataLookupS32(NULL, recipe, "ITER"); // Rejection iterations
     float combineRej = psMetadataLookupF32(NULL, recipe, "COMBINE.REJ"); // Combination threshold
+    float combineSys = psMetadataLookupF32(NULL, recipe, "COMBINE.SYS"); // Combination systematic error
     bool useVariance = psMetadataLookupBool(&mdok, recipe, "VARIANCE"); // Use variance for rejection?
     bool safe = psMetadataLookupBool(&mdok, recipe, "SAFE"); // Be safe when combining small numbers of pixels
@@ -133,6 +134,6 @@
     }
 
-    if (!pmStackCombine(outRO, stack, maskVal | maskBad, maskBad, kernelSize, iter, combineRej, true,
-                        useVariance, safe)) {
+    if (!pmStackCombine(outRO, stack, maskVal | maskBad, maskBad, kernelSize, iter, combineRej, combineSys,
+                        true, useVariance, safe)) {
         psError(PS_ERR_UNKNOWN, false, "Unable to combine input readouts with rejection.");
         psFree(stack);