Index: branches/tap_branches/ppSub/src/ppSubVarianceRescale.c
===================================================================
--- branches/tap_branches/ppSub/src/ppSubVarianceRescale.c	(revision 25900)
+++ branches/tap_branches/ppSub/src/ppSubVarianceRescale.c	(revision 27838)
@@ -35,15 +35,15 @@
     int num = psMetadataLookupS32(&mdok, recipe, "RENORM.NUM");
     if (!mdok) {
-        psError(PS_ERR_BAD_PARAMETER_VALUE, true, "RENORM.NUM is not set in the recipe");
+        psError(PPSUB_ERR_ARGUMENTS, true, "RENORM.NUM is not set in the recipe");
         return false;
     }
     float minValid = psMetadataLookupF32(&mdok, recipe, "RENORM.MIN");
     if (!mdok) {
-        psError(PS_ERR_BAD_PARAMETER_VALUE, true, "RENORM.MIN is not set in the recipe");
+        psError(PPSUB_ERR_ARGUMENTS, true, "RENORM.MIN is not set in the recipe");
         return false;
     }
     float maxValid = psMetadataLookupF32(&mdok, recipe, "RENORM.MAX");
     if (!mdok) {
-        psError(PS_ERR_BAD_PARAMETER_VALUE, true, "RENORM.MAX is not set in the recipe");
+        psError(PPSUB_ERR_ARGUMENTS, true, "RENORM.MAX is not set in the recipe");
         return false;
     }
@@ -54,4 +54,10 @@
     pmReadout *readout = pmFPAfileThisReadout(config->files, view, "PPSUB.OUTPUT"); // Output image
 
+    if (!readout->variance) {
+        // Nothing to renormalise
+        psWarning("Renormalisation of the variance requested, but no variance provided.");
+        return true;
+    }
+
     return pmReadoutVarianceRenormalise(readout, maskBad, num, minValid, maxValid);
 }