--- msort-8.53.orig/configure.ac	2024-11-17 17:40:59.811316465 +0000
+++ msort-8.53/configure.ac	2024-11-17 17:44:22.697222141 +0000
@@ -3,6 +3,8 @@
 AM_CONFIG_HEADER([config.h])
 AM_INIT_AUTOMAKE
 
+AC_USE_SYSTEM_EXTENSIONS
+
 AC_DEFUN([AC_C_LONG_LONG],
 [AC_CACHE_CHECK(for long long int, ac_cv_c_long_long,
 [if test "$GCC" = yes; then
--- msort-8.53.orig/misc.c	2024-11-17 17:40:59.812316460 +0000
+++ msort-8.53/misc.c	2024-11-17 17:42:50.841717590 +0000
@@ -419,7 +419,6 @@
 OpenFile(char *file,char *mode,char *pgname)
 {
   FILE *fp;
-  extern FILE *fopen();
    
   if((fp = fopen(file,mode)) != NULL) return fp;
   else{