diff --git a/crypto/engine/tb_cipher.c b/crypto/engine/tb_cipher.c
index 2716ed7a5..c5a50fc91 100644
--- a/crypto/engine/tb_cipher.c
+++ b/crypto/engine/tb_cipher.c
@@ -68,7 +68,7 @@ void ENGINE_unregister_ciphers(ENGINE *e)
 	engine_table_unregister(&cipher_table, e);
 	}
 
-static void engine_unregister_all_ciphers()
+static void engine_unregister_all_ciphers(void)
 	{
 	engine_table_cleanup(&cipher_table);
 	}
diff --git a/crypto/engine/tb_dh.c b/crypto/engine/tb_dh.c
index 977f9b9c3..c9347235e 100644
--- a/crypto/engine/tb_dh.c
+++ b/crypto/engine/tb_dh.c
@@ -69,7 +69,7 @@ void ENGINE_unregister_DH(ENGINE *e)
 	engine_table_unregister(&dh_table, e);
 	}
 
-static void engine_unregister_all_DH()
+static void engine_unregister_all_DH(void)
 	{
 	engine_table_cleanup(&dh_table);
 	}
diff --git a/crypto/engine/tb_digest.c b/crypto/engine/tb_digest.c
index d2f502e1c..2c4dd6f79 100644
--- a/crypto/engine/tb_digest.c
+++ b/crypto/engine/tb_digest.c
@@ -68,7 +68,7 @@ void ENGINE_unregister_digests(ENGINE *e)
 	engine_table_unregister(&digest_table, e);
 	}
 
-static void engine_unregister_all_digests()
+static void engine_unregister_all_digests(void)
 	{
 	engine_table_cleanup(&digest_table);
 	}
diff --git a/crypto/engine/tb_dsa.c b/crypto/engine/tb_dsa.c
index 1f6d03519..e9209476b 100644
--- a/crypto/engine/tb_dsa.c
+++ b/crypto/engine/tb_dsa.c
@@ -69,7 +69,7 @@ void ENGINE_unregister_DSA(ENGINE *e)
 	engine_table_unregister(&dsa_table, e);
 	}
 
-static void engine_unregister_all_DSA()
+static void engine_unregister_all_DSA(void)
 	{
 	engine_table_cleanup(&dsa_table);
 	}
diff --git a/crypto/engine/tb_rand.c b/crypto/engine/tb_rand.c
index 827e104b2..0b1d031f1 100644
--- a/crypto/engine/tb_rand.c
+++ b/crypto/engine/tb_rand.c
@@ -69,7 +69,7 @@ void ENGINE_unregister_RAND(ENGINE *e)
 	engine_table_unregister(&rand_table, e);
 	}
 
-static void engine_unregister_all_RAND()
+static void engine_unregister_all_RAND(void)
 	{
 	engine_table_cleanup(&rand_table);
 	}
diff --git a/crypto/engine/tb_rsa.c b/crypto/engine/tb_rsa.c
index 85049e8ae..f84fea396 100644
--- a/crypto/engine/tb_rsa.c
+++ b/crypto/engine/tb_rsa.c
@@ -69,7 +69,7 @@ void ENGINE_unregister_RSA(ENGINE *e)
 	engine_table_unregister(&rsa_table, e);
 	}
 
-static void engine_unregister_all_RSA()
+static void engine_unregister_all_RSA(void)
 	{
 	engine_table_cleanup(&rsa_table);
 	}