Index: trunk/psModules/src/camera/pmFPAMaskWeight.c
===================================================================
--- trunk/psModules/src/camera/pmFPAMaskWeight.c	(revision 10240)
+++ trunk/psModules/src/camera/pmFPAMaskWeight.c	(revision 10245)
@@ -218,4 +218,7 @@
     } else {
         // Gain is negative or zero --- just use the read noise
+        if (!readout->weight) {
+            readout->weight = psImageAlloc(readout->image->numCols, readout->image->numRows, PS_TYPE_F32);
+        }
         psImageInit(readout->weight, 0.0);
     }