Index: trunk/psModules/src/astrom/pmAstrometryDistortion.c
===================================================================
--- trunk/psModules/src/astrom/pmAstrometryDistortion.c	(revision 41496)
+++ trunk/psModules/src/astrom/pmAstrometryDistortion.c	(revision 41533)
@@ -340,8 +340,12 @@
     psRegion *region = pmAstromFPAExtent (fpa);
 
+    // XXX psFree (fpa->fromTPA);
+    // XXX psPlaneTransform *myPT = psPlaneTransformAlloc(fpa->toTPA->x->nX+4, fpa->toTPA->x->nY+4);
+    // XXX fpa->fromTPA = psPlaneTransformInvert(myPT, fpa->toTPA, *region, 50);
+    // XXX psFree (myPT);
+
+    // as of r40806, psPlaneTransformInvert supplies the extra order (if non-linear)
     psFree (fpa->fromTPA);
-    psPlaneTransform *myPT = psPlaneTransformAlloc(fpa->toTPA->x->nX+4, fpa->toTPA->x->nY+4);
-    fpa->fromTPA = psPlaneTransformInvert(myPT, fpa->toTPA, *region, 50);
-    psFree (myPT);
+    fpa->fromTPA = psPlaneTransformInvert(NULL, fpa->toTPA, *region, 50, 4);
     psFree (region);