Index: trunk/psModules/src/camera/pmFPAMosaic.c
===================================================================
--- trunk/psModules/src/camera/pmFPAMosaic.c	(revision 13339)
+++ trunk/psModules/src/camera/pmFPAMosaic.c	(revision 13499)
@@ -16,4 +16,5 @@
 #include "pmConfig.h"
 #include "pmAstrometryWCS.h"
+#include "pmFPAExtent.h"
 
 #include "pmFPAMosaic.h"
@@ -1086,4 +1087,15 @@
     pmHDU *sourcePHU = pmHDUGetHighest(source->parent, source, NULL);
 
+    // Need to update NAXIS1, NAXIS2 in the target header, so that when we write a CMF, it has the correct
+    // extent.  I'm not convinced that this is the best way to do this, but it should be, at worst, harmless,
+    // since NAXIS[12] will get overwritten for an image with the proper dimensions.
+    psRegion *naxis = pmChipExtent(target);
+    psMetadataAddS32(targetHDU->header, PS_LIST_TAIL, "NAXIS1", PS_META_REPLACE, "Size in x",
+                     naxis->x1 - naxis->x0);
+    psMetadataAddS32(targetHDU->header, PS_LIST_TAIL, "NAXIS2", PS_META_REPLACE, "Size in y",
+                     naxis->y1 - naxis->y0);
+    psFree(naxis);
+
+
     if (!targetPHU) {
         psError(PS_ERR_UNKNOWN, true, "Unable to find HDU after mosaicking.\n");