--- util/topo.f.orig	2000-08-06 04:28:17.000000000 +0900
+++ util/topo.f	2020-11-21 16:30:48.000000000 +0900
@@ -96,7 +96,7 @@
       COMMON/LEVEL/LR,LC,TLAT,TLON,TLATIN,TLONIN,LATINC,LONINC,LEVEL
 C TLAT POSITIVE NORTH, TLON POSITIVE WEST
 C NOTE TLATIN=6.0/LATINC, TLONIN=6.0/LONINC
-      DATA IMASK/'1FF'X/
+      DATA IMASK/X'1FF'/
       DATA LREC/0/,IRECL/72/,CFILE/'TOPOHRES'/
 C
       CALL DDEST('GETTOP',0)