--- setserial.c
+++ setserial.c
@@ -15,6 +15,9 @@
 #include <termios.h>
 #include <string.h>
 #include <errno.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
 
 #ifdef HAVE_ASM_IOCTLS_H
 #include <asm/ioctls.h>
@@ -718,7 +721,7 @@
 	exit(1);
 }
 
-main(int argc, char **argv)
+int main(int argc, char **argv)
 {
 	int	get_flag = 0, wild_intr_flag = 0;
 	int	c;