Index: gerris/configure
===================================================================
--- gerris.orig/configure	2024-11-23 18:19:28.857569965 +0100
+++ gerris/configure	2024-11-23 18:19:28.853569939 +0100
@@ -12399,7 +12399,7 @@
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
-main () {
+int main () {
   if (sizeof (void *) > sizeof (double))
     return 1;
   return 0;
@@ -12665,7 +12665,7 @@
 #include <glib.h>
 #include <gmodule.h>
 
-main () {
+int main () {
   if (!g_module_supported ())
     return 1;
   return 0;
Index: gerris/configure.ac
===================================================================
--- gerris.orig/configure.ac	2024-11-23 18:19:28.857569965 +0100
+++ gerris/configure.ac	2024-11-23 18:19:28.853569939 +0100
@@ -146,7 +146,7 @@
 # check that pointers can be stored in doubles
 AC_MSG_CHECKING(whether pointers can be stored in doubles)
 AC_TRY_RUN([
-main () {
+int main () {
   if (sizeof (void *) > sizeof (double))
     return 1;
   return 0;
@@ -184,7 +184,7 @@
 #include <glib.h>
 #include <gmodule.h>
 
-main () {
+int main () {
   if (!g_module_supported ())
     return 1;
   return 0;