diff -up libsmi-c5830721/configure.ac.c99 libsmi-c5830721/configure.ac
--- libsmi-c5830721/configure.ac.c99	2024-01-05 09:24:57.348720326 -0500
+++ libsmi-c5830721/configure.ac	2024-01-05 09:26:13.074779292 -0500
@@ -42,8 +42,8 @@ AC_ARG_WITH(cc,
 CC="$withval")
 
 AC_MSG_CHECKING([for additional required compiler flags])
-AC_TRY_RUN([#include <stdio.h>
-  main() {
+AC_TRY_RUN([#include <stdlib.h>
+  int main(void) {
   #ifdef __SUNPRO_C
         exit(0);
   #else
@@ -104,8 +104,8 @@ dirseparator="$withval", dirseparator=""
 
 AC_MSG_CHECKING([for path separator character])
 if test "$pathseparator" = "" ; then
-  AC_TRY_RUN([#include <stdio.h>
-    main() {
+  AC_TRY_RUN([#include <stdlib.h>
+    int main(void) {
     #ifdef _WIN32
 	  exit(0);
     #else
@@ -118,8 +118,8 @@ echo $pathseparator
 
 AC_MSG_CHECKING([for dir separator character])
 if test "$dirseparator" = "" ; then
-  AC_TRY_RUN([#include <stdio.h>
-    main() {
+  AC_TRY_RUN([#include <stdlib.h>
+    int main(void) {
     #ifdef _WIN32
 	  exit(0);
     #else
@@ -144,8 +144,8 @@ AC_MSG_CHECKING([for 64 bit types])
 # "warning: decimal constant is so large that it is unsigned"
 # if used with the (correct) value -9223372036854775808LL.
 #
-AC_TRY_RUN([#include <stdio.h>
-      main() {
+AC_TRY_RUN([#include <stdlib.h>
+      int main(void) {
 	  long long ll;
 	  unsigned long long ull;
 	  exit(0);