diff --git a/include/ma_global.h b/include/ma_global.h
index 5318ff6f..790fb991 100644
--- a/include/ma_global.h
+++ b/include/ma_global.h
@@ -303,7 +303,7 @@ typedef unsigned short ushort;
 #define my_reinterpret_cast(A) (A)
 #define my_const_cast(A) (A)
 #endif
-#if !defined(__attribute__) && (defined(__cplusplus) || !defined(__GNUC__)  || __GNUC__ == 2 && __GNUC_MINOR__ < 8)
+#if !defined(__GNUC__) && !defined(__clang__)
 #define __attribute__(A)
 #endif
 
diff --git a/include/mysql.h b/include/mysql.h
index ea30c4ec..f75ab66f 100644
--- a/include/mysql.h
+++ b/include/mysql.h
@@ -440,7 +440,7 @@ struct st_mysql_client_plugin
   MYSQL_CLIENT_PLUGIN_HEADER
 };
 
-struct st_mysql_client_plugin * STDCALL
+struct st_mysql_client_plugin *
 mysql_load_plugin(struct st_mysql *mysql, const char *name, int type,
                   int argc, ...);
 struct st_mysql_client_plugin * STDCALL
@@ -493,7 +493,7 @@ const char * STDCALL mysql_character_set_name(MYSQL *mysql);
 void STDCALL mysql_get_character_set_info(MYSQL *mysql, MY_CHARSET_INFO *cs);
 int STDCALL mysql_set_character_set(MYSQL *mysql, const char *csname);
 
-my_bool STDCALL mariadb_get_infov(MYSQL *mysql, enum mariadb_value value, void *arg, ...);
+my_bool mariadb_get_infov(MYSQL *mysql, enum mariadb_value value, void *arg, ...);
 my_bool STDCALL mariadb_get_info(MYSQL *mysql, enum mariadb_value value, void *arg);
 MYSQL *		STDCALL mysql_init(MYSQL *mysql);
 int		STDCALL mysql_ssl_set(MYSQL *mysql, const char *key,
@@ -570,8 +570,8 @@ MARIADB_CHARSET_INFO * STDCALL mariadb_get_charset_by_name(const char *csname);
 MARIADB_CHARSET_INFO * STDCALL mariadb_get_charset_by_nr(unsigned int csnr);
 size_t STDCALL mariadb_convert_string(const char *from, size_t *from_len, MARIADB_CHARSET_INFO *from_cs,
                                       char *to, size_t *to_len, MARIADB_CHARSET_INFO *to_cs, int *errorcode);
-int STDCALL mysql_optionsv(MYSQL *mysql,enum mysql_option option, ...);
-int STDCALL mysql_get_optionv(MYSQL *mysql, enum mysql_option option, void *arg, ...);
+int mysql_optionsv(MYSQL *mysql,enum mysql_option option, ...);
+int mysql_get_optionv(MYSQL *mysql, enum mysql_option option, void *arg, ...);
 int STDCALL mysql_get_option(MYSQL *mysql, enum mysql_option option, void *arg);
 unsigned long STDCALL mysql_hex_string(char *to, const char *from, unsigned long len);
 my_socket STDCALL mysql_get_socket(MYSQL *mysql);
diff --git a/include/mysql/client_plugin.h b/include/mysql/client_plugin.h
index eb2cea0a..d6ced69a 100644
--- a/include/mysql/client_plugin.h
+++ b/include/mysql/client_plugin.h
@@ -176,7 +176,7 @@ typedef struct st_mysql_client_plugin_REMOTEIO
   @retval
   a pointer to the loaded plugin, or NULL in case of a failure
 */
-struct st_mysql_client_plugin * STDCALL
+struct st_mysql_client_plugin *
 mysql_load_plugin(struct st_mysql *mysql, const char *name, int type,
                   int argc, ...);
 
diff --git a/libmariadb/mariadb_lib.c b/libmariadb/mariadb_lib.c
index a178ce96..9eb66752 100644
--- a/libmariadb/mariadb_lib.c
+++ b/libmariadb/mariadb_lib.c
@@ -526,13 +526,6 @@ void read_user_name(char *name)
 
 #endif
 
-#ifdef _WIN32
-static my_bool is_NT(void)
-{
-  char *os=getenv("OS");
-  return (os && !strcmp(os, "Windows_NT")) ? 1 : 0;
-}
-#endif
 
 /**************************************************************************
 ** Shut down connection
diff --git a/libmariadb/secure/ma_schannel.c b/libmariadb/secure/ma_schannel.c
index 23dc48a8..67a0f990 100644
--- a/libmariadb/secure/ma_schannel.c
+++ b/libmariadb/secure/ma_schannel.c
@@ -501,7 +501,7 @@ SECURITY_STATUS ma_schannel_handshake_loop(MARIADB_PVIO *pvio, my_bool InitialRe
 
     if (rc == SEC_E_OK  ||
         rc == SEC_I_CONTINUE_NEEDED ||
-        FAILED(rc) && (dwSSPIOutFlags & ISC_RET_EXTENDED_ERROR))
+        (FAILED(rc) && (dwSSPIOutFlags & ISC_RET_EXTENDED_ERROR)))
     {
       if(OutBuffers.cbBuffer && OutBuffers.pvBuffer)
       {
diff --git a/plugins/auth/sha256_pw.c b/plugins/auth/sha256_pw.c
index c141b19f..efd702bd 100644
--- a/plugins/auth/sha256_pw.c
+++ b/plugins/auth/sha256_pw.c
@@ -229,14 +229,14 @@ static int auth_sha256_client(MYSQL_PLUGIN_VIO *vio, MYSQL *mysql)
   der_buffer_len= packet_length;
   /* Load pem and convert it to binary object. New length will be returned
      in der_buffer_len */
-  if (!(der_buffer= ma_load_pem(filebuffer ? filebuffer : packet, &der_buffer_len)))
+  if (!(der_buffer= ma_load_pem(filebuffer ? filebuffer : (char *)packet, &der_buffer_len)))
     goto error;
 
   /* Create context and load public key */
   if (!CryptDecodeObjectEx(X509_ASN_ENCODING, X509_PUBLIC_KEY_INFO,
                            der_buffer, der_buffer_len,
                            CRYPT_ENCODE_ALLOC_FLAG, NULL,
-                           &publicKeyInfo, &publicKeyInfoLen))
+                           &publicKeyInfo, (DWORD *)&publicKeyInfoLen))
     goto error;
   LocalFree(der_buffer);
 
@@ -268,7 +268,7 @@ static int auth_sha256_client(MYSQL_PLUGIN_VIO *vio, MYSQL *mysql)
   if (RSA_public_encrypt(pwlen, (unsigned char *)passwd, rsa_enc_pw, pubkey, RSA_PKCS1_OAEP_PADDING) < 0)
     goto error;
 #elif defined(HAVE_WINCRYPT)
-  if (!CryptEncrypt(pubkey, 0, TRUE, CRYPT_OAEP, passwd, &pwlen, MAX_PW_LEN))
+  if (!CryptEncrypt(pubkey, 0, TRUE, CRYPT_OAEP, passwd, (DWORD *)&pwlen, MAX_PW_LEN))
     goto error;
   /* Windows encrypts as little-endian, while server (openssl) expects
      big-endian, so we have to revert the string */
diff --git a/plugins/pvio/pvio_npipe.c b/plugins/pvio/pvio_npipe.c
index f16beec6..d745027b 100644
--- a/plugins/pvio/pvio_npipe.c
+++ b/plugins/pvio/pvio_npipe.c
@@ -162,7 +162,6 @@ end:
 
 int pvio_npipe_wait_io_or_timeout(MARIADB_PVIO *pvio, my_bool is_read, int timeout)
 {
-  int r= -1;
   DWORD status;
   int save_error;
   struct st_pvio_npipe *cpipe= NULL;
diff --git a/plugins/pvio/pvio_shmem.c b/plugins/pvio/pvio_shmem.c
index 09586c63..86cd2ba1 100644
--- a/plugins/pvio/pvio_shmem.c
+++ b/plugins/pvio/pvio_shmem.c
@@ -243,7 +243,7 @@ my_bool pvio_shm_connect(MARIADB_PVIO *pvio, MA_PVIO_CINFO *cinfo)
   char *shm_name, *shm_suffix, *shm_prefix;
   uchar i= 0;
   int len;
-  DWORD cid;
+  int cid;
   DWORD dwDesiredAccess= EVENT_MODIFY_STATE | SYNCHRONIZE;
   HANDLE hdlConnectRequest= NULL,
          hdlConnectRequestAnswer= NULL,
diff --git a/plugins/pvio/pvio_socket.c b/plugins/pvio/pvio_socket.c
index 737ca15f..6255b372 100644
--- a/plugins/pvio/pvio_socket.c
+++ b/plugins/pvio/pvio_socket.c
@@ -64,6 +64,10 @@
 #define SOCKET_ERROR -1
 #endif
 
+#ifndef INVALID_SOCKET
+#define INVALID_SOCKET -1
+#endif
+
 #define DNS_TIMEOUT 30
 
 #ifndef O_NONBLOCK
@@ -732,7 +736,7 @@ my_bool pvio_socket_connect(MARIADB_PVIO *pvio, MA_PVIO_CINFO *cinfo)
     return 1;
   }
   pvio->data= (void *)csock;
-  csock->socket= -1;
+  csock->socket= INVALID_SOCKET;
   mysql= pvio->mysql= cinfo->mysql;
   pvio->type= cinfo->type;
 
@@ -741,7 +745,7 @@ my_bool pvio_socket_connect(MARIADB_PVIO *pvio, MA_PVIO_CINFO *cinfo)
 #ifndef _WIN32
 #ifdef HAVE_SYS_UN_H
     struct sockaddr_un UNIXaddr;
-    if ((csock->socket = socket(AF_UNIX,SOCK_STREAM,0)) == SOCKET_ERROR)
+    if ((csock->socket = socket(AF_UNIX,SOCK_STREAM,0)) == INVALID_SOCKET)
     {
       PVIO_SET_ERROR(cinfo->mysql, CR_SOCKET_CREATE_ERROR, unknown_sqlstate, 0, errno);
       goto error;
@@ -843,7 +847,7 @@ my_bool pvio_socket_connect(MARIADB_PVIO *pvio, MA_PVIO_CINFO *cinfo)
     {
       csock->socket= socket(save_res->ai_family, save_res->ai_socktype, 
                             save_res->ai_protocol);
-      if (csock->socket == SOCKET_ERROR)
+      if (csock->socket == INVALID_SOCKET)
         /* Errors will be handled after loop finished */
         continue;
 
@@ -881,7 +885,7 @@ my_bool pvio_socket_connect(MARIADB_PVIO *pvio, MA_PVIO_CINFO *cinfo)
     if (bind_res)
       freeaddrinfo(bind_res);
 
-    if (csock->socket == SOCKET_ERROR)
+    if (csock->socket == INVALID_SOCKET)
     {
       PVIO_SET_ERROR(cinfo->mysql, CR_IPSOCK_ERROR, SQLSTATE_UNKNOWN, ER(CR_IPSOCK_ERROR),
                          socket_errno);
@@ -919,7 +923,7 @@ my_bool pvio_socket_connect(MARIADB_PVIO *pvio, MA_PVIO_CINFO *cinfo)
   return 0;
 error:
   /* close socket: MDEV-10891 */
-  if (csock->socket != -1)
+  if (csock->socket != INVALID_SOCKET)
     closesocket(csock->socket);
   if (pvio->data)
   {
@@ -941,11 +945,10 @@ my_bool pvio_socket_close(MARIADB_PVIO *pvio)
   if (pvio->data)
   {
     csock= (struct st_pvio_socket *)pvio->data;
-    if (csock && csock->socket != -1)
+    if (csock && csock->socket != INVALID_SOCKET)
     {
-      r= shutdown(csock->socket ,2);
       r= closesocket(csock->socket);
-      csock->socket= -1;
+      csock->socket= INVALID_SOCKET;
     }
     free((gptr)pvio->data);
     pvio->data= NULL;
diff --git a/unittest/libmariadb/ma_getopt.c b/unittest/libmariadb/ma_getopt.c
index 411f4ba7..00064af1 100644
--- a/unittest/libmariadb/ma_getopt.c
+++ b/unittest/libmariadb/ma_getopt.c
@@ -45,10 +45,9 @@ Cambridge, MA 02139, USA.  */
 #define const
 #endif
 #endif
-
-#include <ma_global.h>				/* Changes for mysys */
-#include <ma_string.h>
-
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
 /* Comment out all this code if we are using the GNU C Library, and are not
    actually compiling the library itself.  This code is part of the GNU C
    Library, but also included in many other GNU distributions.	Compiling