--- a/src/environ.c
+++ b/src/environ.c
@@ -4,7 +4,7 @@
 #endif
 #include "environ.h"
 
-int check_env()
+int check_env(void)
 {
 
 	if (getenv(SHASH_KEY) != NULL
@@ -15,7 +15,7 @@
 }
 
 char *
- get_env_key()
+ get_env_key(void)
 {
 
 	if (getenv(SHASH_KEY) != NULL) {
@@ -26,7 +26,7 @@
 
 }
 
-char *get_env_bit_mode()
+char *get_env_bit_mode(void)
 {
 
 	return getenv(SHASH_KEYMODE);
--- a/src/environ.h
+++ b/src/environ.h
@@ -3,7 +3,7 @@
 #define SHASH_KEY "SHASH_KEY"
 #define SHASH_KEYMODE "SHASH_KEYMODE"
 
-int check_env();
-char * get_env_key();
-char * get_env_bit_mode();
+int check_env(void);
+char * get_env_key(void);
+char * get_env_bit_mode(void);
 
--- a/src/errors.c
+++ b/src/errors.c
@@ -1,5 +1,7 @@
 #include <defines.h>
 
+#include <stdio.h>
+
 extern int quiet;
 
 void err_quit(char *errmsg)
--- a/src/extra.c
+++ b/src/extra.c
@@ -1,5 +1,10 @@
 #include <defines.h>
 
+#include <pwd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+
 #ifdef HAVE_STAT
 
 int check_file(char *filename)
--- a/src/gaaout.c
+++ b/src/gaaout.c
@@ -11,6 +11,11 @@
 #endif
 #endif
 
+void hash_license(void);
+void hash_version(void);
+void list_keygen_algorithms(void);
+int hash_list(void);
+
 void* gaa_malloc( size_t size) {
 void* ret;
 	ret = malloc(size);
--- a/src/random.c
+++ b/src/random.c
@@ -24,7 +24,7 @@
 static FILE *ffd;
 
 word32
-get_rand32()
+get_rand32(void)
 {
 	int fd, x;
 	word32 rand_data;
@@ -46,7 +46,7 @@
 
 
 word8
-get_rand8()
+get_rand8(void)
 {
 
 	int fd, x;
@@ -69,7 +69,7 @@
 
 
 word32
-get_safe_rand32()
+get_safe_rand32(void)
 {
 	int fd, x;
 	word32 rand_data;
@@ -91,7 +91,7 @@
 
 
 word8
-get_safe_rand8()
+get_safe_rand8(void)
 {
 
 	int fd, x;
@@ -131,13 +131,13 @@
 	return 0;
 }
 
-void close_rand()
+void close_rand(void)
 {
 	fclose(ffd);
 }
 
 word32
-get_o_rand32()
+get_o_rand32(void)
 {
 	int x;
 	word32 rand_data;
@@ -152,7 +152,7 @@
 }
 
 word8
-get_o_rand8()
+get_o_rand8(void)
 {
 
 	int x;
--- a/src/random.h
+++ b/src/random.h
@@ -1,14 +1,14 @@
 
 #ifdef HAVE_DEV_RANDOM
 
-word32 get_rand32();
-word8 get_rand8();
-word32 get_safe_rand32();
-word8 get_safe_rand8();
+word32 get_rand32(void);
+word8 get_rand8(void);
+word32 get_safe_rand32(void);
+word8 get_safe_rand8(void);
 
 int open_rand(int);
-void close_rand();
-word32 get_o_rand32();
-word8 get_o_rand8();
+void close_rand(void);
+word32 get_o_rand32(void);
+word8 get_o_rand8(void);
 
 #endif
--- a/src/shash.c
+++ b/src/shash.c
@@ -485,7 +485,7 @@
 	}
 }
 
-int hash_list()
+int hash_list(void)
 {
 	hashid i;
 	char *y;
@@ -715,7 +715,7 @@
 	return counter;
 }
 
-void hash_license()
+void hash_license(void)
 {
 	fprintf(stdout, ("\nCopyright (C) 1999,2001,2002 Nikos Mavroyanopoulos\n"
 "This program is free software; you can redistribute it and/or modify \n"
@@ -733,7 +733,7 @@
 "Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.\n\n"));
 }
 
-void hash_version()
+void hash_version(void)
 {
 	fprintf(stderr, ("shash v.%s (%s-%s-%s)\n"), VERSION, T_CPU,
 		T_VENDOR, T_OS);