diff --git a/test/auth.c b/test/auth.c
index 5086624e..34fade68 100644
--- a/test/auth.c
+++ b/test/auth.c
@@ -7,7 +7,7 @@ unsigned char c[28] = "what do ya want for nothing?";
 
 unsigned char a[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_auth_hmacsha512256(a,c,sizeof c,key);
diff --git a/test/auth2.c b/test/auth2.c
index ba191de4..0433a51e 100644
--- a/test/auth2.c
+++ b/test/auth2.c
@@ -22,7 +22,7 @@ unsigned char c[50] = {
 
 unsigned char a[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_auth_hmacsha256(a,c,sizeof c,key);
diff --git a/test/auth3.c b/test/auth3.c
index b713b388..fcc6e0ea 100644
--- a/test/auth3.c
+++ b/test/auth3.c
@@ -27,7 +27,7 @@ unsigned char a[32] = {
 ,0x7b,0xb1,0x56,0xd3,0xd7,0xb3,0x0d,0x3f
 } ;
 
-main()
+int main(void)
 {
   printf("%d\n",crypto_auth_hmacsha256_verify(a,c,sizeof c,key));
   return 0;
diff --git a/test/auth5.c b/test/auth5.c
index 92d8fea3..ae266e1f 100644
--- a/test/auth5.c
+++ b/test/auth5.c
@@ -8,7 +8,7 @@ unsigned char key[32];
 unsigned char c[10000];
 unsigned char a[32];
 
-main()
+int main(void)
 {
   int clen;
   int i;
diff --git a/test/box.c b/test/box.c
index b57a9883..ab204ca7 100644
--- a/test/box.c
+++ b/test/box.c
@@ -48,7 +48,7 @@ unsigned char m[163] = {
 
 unsigned char c[163];
 
-main()
+int main(void)
 {
   int i;
   crypto_box_curve25519xsalsa20poly1305(
diff --git a/test/box2.c b/test/box2.c
index 0a531142..bfafcc12 100644
--- a/test/box2.c
+++ b/test/box2.c
@@ -48,7 +48,7 @@ unsigned char c[163] = {
 
 unsigned char m[163];
 
-main()
+int main(void)
 {
   int i;
   if (crypto_box_curve25519xsalsa20poly1305_open(
diff --git a/test/box7.c b/test/box7.c
index 809301c1..ab67ee4c 100644
--- a/test/box7.c
+++ b/test/box7.c
@@ -11,7 +11,7 @@ unsigned char m[10000];
 unsigned char c[10000];
 unsigned char m2[10000];
 
-main()
+int main(void)
 {
   int mlen;
   int i;
diff --git a/test/box8.c b/test/box8.c
index 8f2b919a..574b2b67 100644
--- a/test/box8.c
+++ b/test/box8.c
@@ -13,7 +13,7 @@ unsigned char m[10000];
 unsigned char c[10000];
 unsigned char m2[10000];
 
-main()
+int main(void)
 {
   int mlen;
   int i;
diff --git a/test/core1.c b/test/core1.c
index 9a8fc51d..41dcab83 100644
--- a/test/core1.c
+++ b/test/core1.c
@@ -17,7 +17,7 @@ unsigned char c[16] = {
 
 unsigned char firstkey[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_core_hsalsa20(firstkey,zero,shared,c);
diff --git a/test/core2.c b/test/core2.c
index 08402285..cb3387dd 100644
--- a/test/core2.c
+++ b/test/core2.c
@@ -20,7 +20,7 @@ unsigned char c[16] = {
 
 unsigned char secondkey[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_core_hsalsa20(secondkey,nonceprefix,firstkey,c);
diff --git a/test/core3.c b/test/core3.c
index 4c759a5b..4585ce4b 100644
--- a/test/core3.c
+++ b/test/core3.c
@@ -24,7 +24,7 @@ unsigned char output[64 * 256 * 256];
 
 unsigned char h[32];
 
-main()
+int main(void)
 {
   int i;
   long long pos = 0;
diff --git a/test/core4.c b/test/core4.c
index 1f238c5e..08489778 100644
--- a/test/core4.c
+++ b/test/core4.c
@@ -20,7 +20,7 @@ unsigned char c[16] = {
 
 unsigned char out[64];
 
-main()
+int main(void)
 {
   int i;
   crypto_core_salsa20(out,in,k,c);
diff --git a/test/core5.c b/test/core5.c
index 6353477d..425d9ef8 100644
--- a/test/core5.c
+++ b/test/core5.c
@@ -20,7 +20,7 @@ unsigned char c[16] = {
 
 unsigned char out[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_core_hsalsa20(out,in,k,c);
diff --git a/test/core6.c b/test/core6.c
index 67f35df9..52f294e9 100644
--- a/test/core6.c
+++ b/test/core6.c
@@ -32,7 +32,7 @@ void print(unsigned char *x,unsigned char *y)
   }
 }
 
-main()
+int main(void)
 {
   crypto_core_salsa20(out,in,k,c);
   print(out,c);
diff --git a/test/hash.c b/test/hash.c
index 8de470aa..e477aec4 100644
--- a/test/hash.c
+++ b/test/hash.c
@@ -4,7 +4,7 @@
 unsigned char x[8] = "testing\n";
 unsigned char h[crypto_hash_BYTES];
 
-int main()
+int main(void)
 {
   int i;
   crypto_hash(h,x,sizeof x);
diff --git a/test/hash3.c b/test/hash3.c
index 10b89b90..2bc5beae 100644
--- a/test/hash3.c
+++ b/test/hash3.c
@@ -4,7 +4,7 @@
 unsigned char x[8] = "testing\n";
 unsigned char h[crypto_hash_sha512_BYTES];
 
-int main()
+int main(void)
 {
   int i;
   crypto_hash_sha512(h,x,sizeof x);
diff --git a/test/onetimeauth.c b/test/onetimeauth.c
index 60a2df14..5d755bdf 100644
--- a/test/onetimeauth.c
+++ b/test/onetimeauth.c
@@ -30,7 +30,7 @@ unsigned char c[131] = {
 
 unsigned char a[16];
 
-main()
+int main(void)
 {
   int i;
   crypto_onetimeauth_poly1305(a,c,131,rs);
diff --git a/test/onetimeauth2.c b/test/onetimeauth2.c
index 64c1a9cd..523ab13f 100644
--- a/test/onetimeauth2.c
+++ b/test/onetimeauth2.c
@@ -33,7 +33,7 @@ unsigned char a[16] = {
 ,0x2a,0x7d,0xfb,0x4b,0x3d,0x33,0x05,0xd9
 } ;
 
-main()
+int main(void)
 {
   printf("%d\n",crypto_onetimeauth_poly1305_verify(a,c,131,rs));
   return 0;
diff --git a/test/onetimeauth7.c b/test/onetimeauth7.c
index e4b38618..859b0380 100644
--- a/test/onetimeauth7.c
+++ b/test/onetimeauth7.c
@@ -8,7 +8,7 @@ unsigned char key[32];
 unsigned char c[10000];
 unsigned char a[16];
 
-main()
+int main(void)
 {
   int clen;
   int i;
diff --git a/test/scalarmult.c b/test/scalarmult.c
index d9265954..961f2fc1 100644
--- a/test/scalarmult.c
+++ b/test/scalarmult.c
@@ -10,7 +10,7 @@ unsigned char alicesk[32] = {
 
 unsigned char alicepk[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_scalarmult_curve25519_base(alicepk,alicesk);
diff --git a/test/scalarmult2.c b/test/scalarmult2.c
index 90e6360d..addef3ee 100644
--- a/test/scalarmult2.c
+++ b/test/scalarmult2.c
@@ -10,7 +10,7 @@ unsigned char bobsk[32] = {
 
 unsigned char bobpk[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_scalarmult_curve25519_base(bobpk,bobsk);
diff --git a/test/scalarmult5.c b/test/scalarmult5.c
index 14f8159d..4433f669 100644
--- a/test/scalarmult5.c
+++ b/test/scalarmult5.c
@@ -17,7 +17,7 @@ unsigned char bobpk[32] = {
 
 unsigned char k[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_scalarmult_curve25519(k,alicesk,bobpk);
diff --git a/test/scalarmult6.c b/test/scalarmult6.c
index 89bf9bdd..8500569e 100644
--- a/test/scalarmult6.c
+++ b/test/scalarmult6.c
@@ -17,7 +17,7 @@ unsigned char alicepk[32] = {
 
 unsigned char k[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_scalarmult_curve25519(k,bobsk,alicepk);
diff --git a/test/secretbox.c b/test/secretbox.c
index 773f5b62..db1d0a52 100644
--- a/test/secretbox.c
+++ b/test/secretbox.c
@@ -41,7 +41,7 @@ unsigned char m[163] = {
 
 unsigned char c[163];
 
-main()
+int main(void)
 {
   int i;
   crypto_secretbox_xsalsa20poly1305(
diff --git a/test/secretbox2.c b/test/secretbox2.c
index b6a2a937..ae89ba9c 100644
--- a/test/secretbox2.c
+++ b/test/secretbox2.c
@@ -41,7 +41,7 @@ unsigned char c[163] = {
 
 unsigned char m[163];
 
-main()
+int main(void)
 {
   int i;
   if (crypto_secretbox_xsalsa20poly1305_open(
diff --git a/test/secretbox7.c b/test/secretbox7.c
index d4be9b49..45c9c68e 100644
--- a/test/secretbox7.c
+++ b/test/secretbox7.c
@@ -8,7 +8,7 @@ unsigned char m[10000];
 unsigned char c[10000];
 unsigned char m2[10000];
 
-main()
+int main(void)
 {
   int mlen;
   int i;
diff --git a/test/secretbox8.c b/test/secretbox8.c
index 3e0e8f80..9562c7c6 100644
--- a/test/secretbox8.c
+++ b/test/secretbox8.c
@@ -10,7 +10,7 @@ unsigned char m[10000];
 unsigned char c[10000];
 unsigned char m2[10000];
 
-main()
+int main(void)
 {
   int mlen;
   int i;
diff --git a/test/stream.c b/test/stream.c
index ebb39398..9fbe1db3 100644
--- a/test/stream.c
+++ b/test/stream.c
@@ -19,7 +19,7 @@ unsigned char output[4194304];
 
 unsigned char h[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_stream_xsalsa20(output,4194304,nonce,firstkey);
diff --git a/test/stream2.c b/test/stream2.c
index 12f13de4..945360e8 100644
--- a/test/stream2.c
+++ b/test/stream2.c
@@ -17,7 +17,7 @@ unsigned char output[4194304];
 
 unsigned char h[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_stream_salsa20(output,4194304,noncesuffix,secondkey);
diff --git a/test/stream3.c b/test/stream3.c
index 7798dc18..887caf01 100644
--- a/test/stream3.c
+++ b/test/stream3.c
@@ -16,7 +16,7 @@ unsigned char nonce[24] = {
 
 unsigned char rs[32];
 
-main()
+int main(void)
 {
   int i;
   crypto_stream_xsalsa20(rs,32,nonce,firstkey);
diff --git a/test/stream4.c b/test/stream4.c
index 84d8c523..f2771dd6 100644
--- a/test/stream4.c
+++ b/test/stream4.c
@@ -40,7 +40,7 @@ unsigned char m[163] = {
 
 unsigned char c[163];
 
-main()
+int main(void)
 {
   int i;
   crypto_stream_xsalsa20_xor(c,m,163,nonce,firstkey);