diff --git a/src/client.c b/src/client.c
index 5f3eb781..855df196 100644
--- a/src/client.c
+++ b/src/client.c
@@ -103,7 +103,7 @@ static long send_query_recvcnt = 0;
 static int hostname_maxlen = 0xFF;
 
 void
-client_init()
+client_init(void)
 {
 	running = 1;
 	rand_seed = ((unsigned int) rand()) & 0xFFFF;
@@ -124,13 +124,13 @@ client_init()
 }
 
 void
-client_stop()
+client_stop(void)
 {
 	running = 0;
 }
 
 enum connection
-client_get_conn()
+client_get_conn(void)
 {
 	return conn;
 }
@@ -175,7 +175,7 @@ client_set_qtype(char *qtype)
 }
 
 char *
-client_get_qtype()
+client_get_qtype(void)
 {
 	char *c = "UNDEFINED";
 
@@ -225,7 +225,7 @@ client_set_hostname_maxlen(int i)
 }
 
 const char *
-client_get_raw_addr()
+client_get_raw_addr(void)
 {
 	return format_addr(&raw_serv, raw_serv_len);
 }
diff --git a/src/common.c b/src/common.c
index a1475795..8d2fec0d 100644
--- a/src/common.c
+++ b/src/common.c
@@ -276,7 +276,7 @@ do_pidfile(char *pidfile)
 }
 
 void
-do_detach()
+do_detach(void)
 {
 #ifndef WINDOWS32
 	fprintf(stderr, "Detaching from terminal...\n");
diff --git a/src/fw_query.c b/src/fw_query.c
index 873307a1..651c004b 100644
--- a/src/fw_query.c
+++ b/src/fw_query.c
@@ -20,7 +20,7 @@
 static struct fw_query fwq[FW_QUERY_CACHE_SIZE];
 static int fwq_ix;
 
-void fw_query_init()
+void fw_query_init(void)
 {
 	memset(fwq, 0, sizeof(struct fw_query) * FW_QUERY_CACHE_SIZE);
 	fwq_ix = 0;
diff --git a/tests/base32.c b/tests/base32.c
index 8f36c921..a9ab6e64 100644
--- a/tests/base32.c
+++ b/tests/base32.c
@@ -119,7 +119,7 @@ START_TEST(test_base32_blksize)
 END_TEST
 
 TCase *
-test_base32_create_tests()
+test_base32_create_tests(void)
 {
 	TCase *tc;
 
diff --git a/tests/base64.c b/tests/base64.c
index bf72e43d..7956f9be 100644
--- a/tests/base64.c
+++ b/tests/base64.c
@@ -132,7 +132,7 @@ START_TEST(test_base64_blksize)
 END_TEST
 
 TCase *
-test_base64_create_tests()
+test_base64_create_tests(void)
 {
 	TCase *tc;
 
diff --git a/tests/common.c b/tests/common.c
index 0b1fcab6..87fe3307 100644
--- a/tests/common.c
+++ b/tests/common.c
@@ -281,7 +281,7 @@ START_TEST(test_parse_format_ipv4_mapped_ipv6)
 END_TEST
 
 TCase *
-test_common_create_tests()
+test_common_create_tests(void)
 {
 	TCase *tc;
 	int sock;
diff --git a/tests/dns.c b/tests/dns.c
index 7127a154..5aa60789 100644
--- a/tests/dns.c
+++ b/tests/dns.c
@@ -250,7 +250,7 @@ dump_packet(char *buf, size_t len)
 }
 
 TCase *
-test_dns_create_tests()
+test_dns_create_tests(void)
 {
 	TCase *tc;
 
diff --git a/tests/encoding.c b/tests/encoding.c
index 3a57ce10..eac52c93 100644
--- a/tests/encoding.c
+++ b/tests/encoding.c
@@ -93,7 +93,7 @@ START_TEST(test_build_hostname)
 END_TEST
 
 TCase *
-test_encoding_create_tests()
+test_encoding_create_tests(void)
 {
 	TCase *tc;
 
diff --git a/tests/fw_query.c b/tests/fw_query.c
index 937c1d15..1e3a16f5 100644
--- a/tests/fw_query.c
+++ b/tests/fw_query.c
@@ -76,7 +76,7 @@ START_TEST(test_fw_query_edge)
 END_TEST
 
 TCase *
-test_fw_query_create_tests()
+test_fw_query_create_tests(void)
 {
 	TCase *tc;
 
diff --git a/tests/login.c b/tests/login.c
index b973a728..0c37c7f0 100644
--- a/tests/login.c
+++ b/tests/login.c
@@ -59,7 +59,7 @@ START_TEST(test_login_hash_short)
 END_TEST
 
 TCase *
-test_login_create_tests()
+test_login_create_tests(void)
 {
 	TCase *tc;
 
diff --git a/tests/read.c b/tests/read.c
index fea7b63c..01baab78 100644
--- a/tests/read.c
+++ b/tests/read.c
@@ -270,7 +270,7 @@ END_TEST
 
 
 TCase *
-test_read_create_tests()
+test_read_create_tests(void)
 {
 	TCase *tc;
 
diff --git a/tests/test.c b/tests/test.c
index eda792b4..a816a99b 100644
--- a/tests/test.c
+++ b/tests/test.c
@@ -24,7 +24,7 @@
 #include "test.h"
 
 int
-main()
+main(void)
 {
 	SRunner *runner;
 	Suite *iodine;
diff --git a/tests/test.h b/tests/test.h
index d3f79857..25ca4fd1 100644
--- a/tests/test.h
+++ b/tests/test.h
@@ -18,15 +18,15 @@
 #ifndef __TEST_H__
 #define __TEST_H__
 
-TCase *test_base32_create_tests();
-TCase *test_base64_create_tests();
-TCase *test_common_create_tests();
-TCase *test_dns_create_tests();
-TCase *test_encoding_create_tests();
-TCase *test_read_create_tests();
-TCase *test_login_create_tests();
-TCase *test_user_create_tests();
-TCase *test_fw_query_create_tests();
+TCase *test_base32_create_tests(void);
+TCase *test_base64_create_tests(void);
+TCase *test_common_create_tests(void);
+TCase *test_dns_create_tests(void);
+TCase *test_encoding_create_tests(void);
+TCase *test_read_create_tests(void);
+TCase *test_login_create_tests(void);
+TCase *test_user_create_tests(void);
+TCase *test_fw_query_create_tests(void);
 
 char *va_str(const char *, ...);
 
diff --git a/tests/user.c b/tests/user.c
index c565e8fd..bf46db17 100644
--- a/tests/user.c
+++ b/tests/user.c
@@ -170,7 +170,7 @@ START_TEST(test_find_available_user_small_net)
 END_TEST
 
 TCase *
-test_user_create_tests()
+test_user_create_tests(void)
 {
 	TCase *tc;