Index: trunk/ppImage/src/ppImageOptions.c
===================================================================
--- trunk/ppImage/src/ppImageOptions.c	(revision 17685)
+++ trunk/ppImage/src/ppImageOptions.c	(revision 17688)
@@ -257,8 +257,9 @@
 
     // even if not requested explicitly, if any of these are set, build an internal mask and weight:
-    if (options->doDark || options->doShutter || options->doFlat || options->doPhotom) {
+    if (options->doBias || options->doOverscan || options->doDark || options->doShutter || options->doFlat ||
+        options->doPhotom) {
         options->doMaskBuild = true;
         options->doWeightBuild = true;
-    } else if (options->doMask || options->doBias || options->doOverscan) {
+    } else if (options->doMask) {
         options->doMaskBuild = true;
     }