diff --git a/lib/cshutdn.c b/lib/cshutdn.c
index c8b40dc321..aeea9bdc3e 100644
--- a/lib/cshutdn.c
+++ b/lib/cshutdn.c
@@ -498,7 +498,7 @@ void Curl_cshutdn_setfds(struct cshutdn *cshutdn,
       Curl_detach_connection(data);
 
       for(i = 0; i < ps.num; i++) {
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
@@ -506,7 +506,7 @@ void Curl_cshutdn_setfds(struct cshutdn *cshutdn,
           FD_SET(ps.sockets[i], read_fd_set);
         if(ps.actions[i] & CURL_POLL_OUT)
           FD_SET(ps.sockets[i], write_fd_set);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
         if((ps.actions[i] & (CURL_POLL_OUT | CURL_POLL_IN)) &&
diff --git a/lib/multi.c b/lib/multi.c
index 926698a423..8543bfa8e5 100644
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -1154,7 +1154,7 @@ CURLMcode curl_multi_fdset(CURLM *m,
         if(!FDSET_SOCK(ps.sockets[i]))
           /* pretend it does not exist */
           continue;
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
@@ -1162,7 +1162,7 @@ CURLMcode curl_multi_fdset(CURLM *m,
           FD_SET(ps.sockets[i], read_fd_set);
         if(ps.actions[i] & CURL_POLL_OUT)
           FD_SET(ps.sockets[i], write_fd_set);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
         if((int)ps.sockets[i] > this_max_fd)
diff --git a/src/tool_cb_rea.c b/src/tool_cb_rea.c
index 8268d0a1a3..1c8e99b99e 100644
--- a/src/tool_cb_rea.c
+++ b/src/tool_cb_rea.c
@@ -71,12 +71,12 @@ size_t tool_read_cb(char *buffer, size_t sz, size_t nmemb, void *userdata)
       timeout.tv_usec = (int)((wait%1000)*1000);
 
       FD_ZERO(&bits);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
       FD_SET(per->infd, &bits);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
       if(!select(per->infd + 1, &bits, NULL, NULL, &timeout))
@@ -161,12 +161,12 @@ int tool_readbusy_cb(void *clientp,
       timeout.tv_usec = 1000;
 
       FD_ZERO(&bits);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
       FD_SET(per->infd, &bits);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
       select(per->infd + 1, &bits, NULL, NULL, &timeout);
diff --git a/tests/libtest/lib1960.c b/tests/libtest/lib1960.c
index 4fb7247073..ef8b3b8308 100644
--- a/tests/libtest/lib1960.c
+++ b/tests/libtest/lib1960.c
@@ -64,7 +64,7 @@ static int sockopt_cb(void *clientp,
   return CURL_SOCKOPT_ALREADY_CONNECTED;
 }
 
-#if defined(__AMIGA__)
+#ifdef __AMIGA__
 #define my_inet_pton(x,y,z) inet_pton(x,(unsigned char *)y,z)
 #else
 #define my_inet_pton(x,y,z) inet_pton(x,y,z)
diff --git a/tests/libtest/lib530.c b/tests/libtest/lib530.c
index d971799da8..3a15bfb0a2 100644
--- a/tests/libtest/lib530.c
+++ b/tests/libtest/lib530.c
@@ -235,12 +235,12 @@ static void t530_updateFdSet(struct t530_Sockets *sockets, fd_set* fdset,
 {
   int i;
   for(i = 0; i < sockets->count; ++i) {
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
     FD_SET(sockets->sockets[i], fdset);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
     if(*maxFd < sockets->sockets[i] + 1) {
diff --git a/tests/libtest/lib582.c b/tests/libtest/lib582.c
index fbd329b64a..7ba53aca3d 100644
--- a/tests/libtest/lib582.c
+++ b/tests/libtest/lib582.c
@@ -182,12 +182,12 @@ static void t582_updateFdSet(struct t582_Sockets *sockets, fd_set* fdset,
 {
   int i;
   for(i = 0; i < sockets->count; ++i) {
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
     FD_SET(sockets->sockets[i], fdset);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
     if(*maxFd < sockets->sockets[i] + 1) {
diff --git a/tests/server/mqttd.c b/tests/server/mqttd.c
index 76ef715011..d8946127da 100644
--- a/tests/server/mqttd.c
+++ b/tests/server/mqttd.c
@@ -666,12 +666,12 @@ static bool mqttd_incoming(curl_socket_t listenfd)
     FD_ZERO(&fds_err);
 
     /* there's always a socket to wait for */
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
     FD_SET(sockfd, &fds_read);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
 
diff --git a/tests/server/sockfilt.c b/tests/server/sockfilt.c
index c17bca34bf..c8b21beee9 100644
--- a/tests/server/sockfilt.c
+++ b/tests/server/sockfilt.c
@@ -965,12 +965,12 @@ static bool juggle(curl_socket_t *sockfdp,
   FD_ZERO(&fds_write);
   FD_ZERO(&fds_err);
 
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
   FD_SET((curl_socket_t)fileno(stdin), &fds_read);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
 
@@ -981,12 +981,12 @@ static bool juggle(curl_socket_t *sockfdp,
     /* server mode */
     sockfd = listenfd;
     /* there's always a socket to wait for */
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
     FD_SET(sockfd, &fds_read);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
     maxfd = (int)sockfd;
@@ -1002,12 +1002,12 @@ static bool juggle(curl_socket_t *sockfdp,
     }
     else {
       /* there's always a socket to wait for */
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
       FD_SET(sockfd, &fds_read);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
       maxfd = (int)sockfd;
@@ -1019,12 +1019,12 @@ static bool juggle(curl_socket_t *sockfdp,
     sockfd = *sockfdp;
     /* sockfd turns CURL_SOCKET_BAD when our connection has been closed */
     if(CURL_SOCKET_BAD != sockfd) {
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
       FD_SET(sockfd, &fds_read);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
       maxfd = (int)sockfd;
diff --git a/tests/server/socksd.c b/tests/server/socksd.c
index 70e27af2ff..d991f71922 100644
--- a/tests/server/socksd.c
+++ b/tests/server/socksd.c
@@ -629,35 +629,35 @@ static bool socksd_incoming(curl_socket_t listenfd)
     FD_ZERO(&fds_err);
 
     /* there's always a socket to wait for */
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
     FD_SET(sockfd, &fds_read);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
 
     for(i = 0; i < 2; i++) {
       if(c[i].used) {
         curl_socket_t fd = c[i].clientfd;
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
         FD_SET(fd, &fds_read);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
         if((int)fd > maxfd)
           maxfd = (int)fd;
         fd = c[i].remotefd;
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
         FD_SET(fd, &fds_read);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
         if((int)fd > maxfd)
diff --git a/tests/server/sws.c b/tests/server/sws.c
index f49f22339d..74a5addd38 100644
--- a/tests/server/sws.c
+++ b/tests/server/sws.c
@@ -830,12 +830,12 @@ static int sws_get_request(curl_socket_t sock, struct sws_httprequest *req)
           FD_ZERO(&input);
           FD_ZERO(&output);
           got = 0;
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
           FD_SET(sock, &input);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
           do {
@@ -1307,12 +1307,12 @@ static curl_socket_t connect_to(const char *ipaddr, unsigned short port)
       timeout.tv_sec = 1; /* 1000 ms */
 
       FD_ZERO(&output);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
       FD_SET(serverfd, &output);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
       while(1) {
@@ -1439,12 +1439,12 @@ static void http_connect(curl_socket_t *infdp,
       /* listener socket is monitored to allow client to establish
          secondary tunnel only when this tunnel is not established
          and primary one is fully operational */
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
       FD_SET(rootfd, &input);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
       maxfd = rootfd;
@@ -1456,12 +1456,12 @@ static void http_connect(curl_socket_t *infdp,
       if(clientfd[i] != CURL_SOCKET_BAD) {
         if(poll_client_rd[i]) {
           /* unless told not to do so, monitor readability */
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
           FD_SET(clientfd[i], &input);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
           if(clientfd[i] > maxfd)
@@ -1470,12 +1470,12 @@ static void http_connect(curl_socket_t *infdp,
         if(poll_client_wr[i] && toc[i]) {
           /* unless told not to do so, monitor writability
              if there is data ready to be sent to client */
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
           FD_SET(clientfd[i], &output);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
           if(clientfd[i] > maxfd)
@@ -1486,12 +1486,12 @@ static void http_connect(curl_socket_t *infdp,
       if(serverfd[i] != CURL_SOCKET_BAD) {
         if(poll_server_rd[i]) {
           /* unless told not to do so, monitor readability */
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
           FD_SET(serverfd[i], &input);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
           if(serverfd[i] > maxfd)
@@ -1500,12 +1500,12 @@ static void http_connect(curl_socket_t *infdp,
         if(poll_server_wr[i] && tos[i]) {
           /* unless told not to do so, monitor writability
              if there is data ready to be sent to server */
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
           FD_SET(serverfd[i], &output);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
           if(serverfd[i] > maxfd)
@@ -2322,12 +2322,12 @@ static int test_sws(int argc, char *argv[])
 
     for(socket_idx = 0; socket_idx < num_sockets; ++socket_idx) {
       /* Listen on all sockets */
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warith-conversion"
 #endif
       FD_SET(all_sockets[socket_idx], &input);
-#if defined(__DJGPP__)
+#ifdef __DJGPP__
 #pragma GCC diagnostic pop
 #endif
       if(all_sockets[socket_idx] > maxfd)