--- db5.3-5.3.28+dfsg2.orig/dist/aclocal/mutex.m4
+++ db5.3-5.3.28+dfsg2/dist/aclocal/mutex.m4
@@ -5,7 +5,7 @@ AC_DEFUN(AM_PTHREADS_SHARED, [
 AC_TRY_RUN([
 #include <stdlib.h>
 #include <pthread.h>
-main() {
+int main() {
 	pthread_cond_t cond;
 	pthread_mutex_t mutex;
 	pthread_condattr_t condattr;
@@ -49,7 +49,7 @@ AC_DEFUN(AM_PTHREADS_PRIVATE, [
 AC_TRY_RUN([
 #include <stdlib.h>
 #include <pthread.h>
-main() {
+int main() {
 	pthread_cond_t cond;
 	pthread_mutex_t mutex;
 	pthread_condattr_t condattr;
@@ -89,7 +89,7 @@ AC_DEFUN(AM_PTHREADS_CONDVAR_DUPINITCHK,
 AC_TRY_RUN([
 #include <stdlib.h>
 #include <pthread.h>
-main() {
+int main() {
 	pthread_cond_t cond;
 	pthread_condattr_t condattr;
 	exit(pthread_condattr_init(&condattr) ||
@@ -110,7 +110,7 @@ AC_DEFUN(AM_PTHREADS_RWLOCKVAR_DUPINITCH
 AC_TRY_RUN([
 #include <stdlib.h>
 #include <pthread.h>
-main() {
+int main() {
 	pthread_rwlock_t rwlock;
 	pthread_rwlockattr_t rwlockattr;
 	exit(pthread_rwlockattr_init(&rwlockattr) ||