Index: trunk/ppSub/src/ppSubReadout.c
===================================================================
--- trunk/ppSub/src/ppSubReadout.c	(revision 17372)
+++ trunk/ppSub/src/ppSubReadout.c	(revision 17728)
@@ -89,4 +89,13 @@
     }
 
+    if (!pmReadoutMaskNonfinite(inRO, maskBad)) {
+        psError(PS_ERR_UNKNOWN, false, "Unable to mask non-finite pixels in input.");
+        return false;
+    }
+    if (!pmReadoutMaskNonfinite(refRO, maskBad)) {
+        psError(PS_ERR_UNKNOWN, false, "Unable to mask non-finite pixels in reference.");
+        return false;
+    }
+
     psVector *optWidths = NULL;         // Vector with FWHMs for optimum search
     if (optimum) {