Index: trunk/pswarp/src/pswarpMapGrid.c
===================================================================
--- trunk/pswarp/src/pswarpMapGrid.c	(revision 23487)
+++ trunk/pswarp/src/pswarpMapGrid.c	(revision 31878)
@@ -32,9 +32,7 @@
     int Ny = src->image->numRows + src->image->row0;
 
-    // allocate an extra superpixel to carry the remainder
-    int nXpts = Nx / nXpix;
-    int nYpts = Ny / nYpix;
-    if (Nx % nXpix) nXpts ++;
-    if (Ny % nYpix) nYpts ++;
+    // always allocate an extra superpixel to handle spillover
+    int nXpts = (int)(Nx / nXpix) + 1;
+    int nYpts = (int)(Ny / nYpix) + 1;
 
     // create the grid of maps