diff -up nmap-6.40/nbase/nbase.h.fdsafe nmap-6.40/nbase/nbase.h
--- nmap-6.40/nbase/nbase.h.fdsafe	2013-07-29 00:08:48.000000000 +0200
+++ nmap-6.40/nbase/nbase.h	2014-04-09 17:30:19.579033118 +0200
@@ -369,37 +369,41 @@ extern "C" int vsnprintf (char *, size_t
 #endif
 
 
-#ifdef WIN32
-#define CHECKED_FD_SET FD_SET
-#else
-#define CHECKED_FD_SET(fd, set) \
-  do { \
-    if ((fd) < FD_SETSIZE) { \
-      FD_SET((fd), (set)); \
-    } else { \
-      fprintf(stderr, "%s:%ld: Attempt to FD_SET fd %d, which is not less than" \
-        " FD_SETSIZE (%d). Try using a lower parallelism.", \
-        __FILE__, (long int) __LINE__, (fd), FD_SETSIZE); \
-      abort(); \
-    } \
-  } while (0)
+static inline int checked_fd_isset(int fd, const fd_set *fds) {
+#ifndef WIN32
+  if (fd >= FD_SETSIZE) {
+    fprintf(stderr, "Attempt to FD_ISSET fd %d, which is not less than "
+                    "FD_SETSIZE (%d). Try using a lower parallelism.",
+                    fd, FD_SETSIZE);
+    abort();
+  }
 #endif
+  return FD_ISSET(fd, fds);
+}
 
-#ifdef WIN32
-#define CHECKED_FD_CLR FD_CLR
-#else
-#define CHECKED_FD_CLR(fd, set) \
-  do { \
-    if ((fd) < FD_SETSIZE) { \
-      FD_CLR((fd), (set)); \
-    } else { \
-      fprintf(stderr, "%s:%ld: Attempt to FD_CLR fd %d, which is not less than" \
-        " FD_SETSIZE (%d). Try using a lower parallelism.", \
-        __FILE__, (long int) __LINE__, (fd), FD_SETSIZE); \
-      abort(); \
-    } \
-  } while (0)
+static inline void checked_fd_clr(int fd, fd_set *fds) {
+#ifndef WIN32
+  if (fd >= FD_SETSIZE) {
+    fprintf(stderr, "Attempt to FD_CLR fd %d, which is not less than "
+                    "FD_SETSIZE (%d). Try using a lower parallelism.",
+                    fd, FD_SETSIZE);
+    abort();
+  }
 #endif
+  FD_CLR(fd, fds);
+}
+
+static inline void checked_fd_set(int fd, fd_set *fds) {
+#ifndef WIN32
+  if (fd >= FD_SETSIZE) {
+    fprintf(stderr, "Attempt to FD_SET fd %d, which is not less than "
+                    "FD_SETSIZE (%d). Try using a lower parallelism.",
+                    fd, FD_SETSIZE);
+    abort();
+  }
+#endif
+  FD_SET(fd, fds);
+}
 
 
 #ifdef __cplusplus
diff -up nmap-6.40/nsock/src/engine_select.c.fdsafe nmap-6.40/nsock/src/engine_select.c
--- nmap-6.40/nsock/src/engine_select.c.fdsafe	2013-07-29 00:08:48.000000000 +0200
+++ nmap-6.40/nsock/src/engine_select.c	2014-04-09 17:30:19.579033118 +0200
@@ -174,18 +174,18 @@ int select_iod_unregister(mspool *nsp, m
     if (iod->pcap) {
       int sd = ((mspcap *)iod->pcap)->pcap_desc;
       if (sd >= 0) {
-        CHECKED_FD_CLR(sd, &sinfo->fds_master_r);
-        CHECKED_FD_CLR(sd, &sinfo->fds_results_r);
+        checked_fd_clr(sd, &sinfo->fds_master_r);
+        checked_fd_clr(sd, &sinfo->fds_results_r);
       }
     } else
 #endif
     {
-      CHECKED_FD_CLR(iod->sd, &sinfo->fds_master_r);
-      CHECKED_FD_CLR(iod->sd, &sinfo->fds_master_w);
-      CHECKED_FD_CLR(iod->sd, &sinfo->fds_master_x);
-      CHECKED_FD_CLR(iod->sd, &sinfo->fds_results_r);
-      CHECKED_FD_CLR(iod->sd, &sinfo->fds_results_w);
-      CHECKED_FD_CLR(iod->sd, &sinfo->fds_results_x);
+      checked_fd_clr(iod->sd, &sinfo->fds_master_r);
+      checked_fd_clr(iod->sd, &sinfo->fds_master_w);
+      checked_fd_clr(iod->sd, &sinfo->fds_master_x);
+      checked_fd_clr(iod->sd, &sinfo->fds_results_r);
+      checked_fd_clr(iod->sd, &sinfo->fds_results_w);
+      checked_fd_clr(iod->sd, &sinfo->fds_results_x);
     }
 
     if (sinfo->max_sd == iod->sd)
@@ -209,23 +209,23 @@ int select_iod_modify(mspool *nsp, msiod
 
   /* -- set events -- */
   if (ev_set & EV_READ)
-    CHECKED_FD_SET(sd, &sinfo->fds_master_r);
+    checked_fd_set(sd, &sinfo->fds_master_r);
 
   if (ev_set & EV_WRITE)
-    CHECKED_FD_SET(sd, &sinfo->fds_master_w);
+    checked_fd_set(sd, &sinfo->fds_master_w);
 
   if (ev_set & EV_EXCEPT)
-    CHECKED_FD_SET(sd, &sinfo->fds_master_x);
+    checked_fd_set(sd, &sinfo->fds_master_x);
 
   /* -- clear events -- */
   if (ev_clr & EV_READ)
-    CHECKED_FD_CLR(sd, &sinfo->fds_master_r);
+    checked_fd_clr(sd, &sinfo->fds_master_r);
 
   if (ev_clr & EV_WRITE)
-    CHECKED_FD_CLR(sd, &sinfo->fds_master_w);
+    checked_fd_clr(sd, &sinfo->fds_master_w);
 
   if (ev_clr & EV_EXCEPT)
-    CHECKED_FD_CLR(sd, &sinfo->fds_master_x);
+    checked_fd_clr(sd, &sinfo->fds_master_x);
 
 
   /* -- update max_sd -- */
@@ -335,7 +335,7 @@ static inline int get_evmask(const mspoo
 #if HAVE_PCAP
 #ifndef PCAP_CAN_DO_SELECT
   if (nsi->pcap) {
-    /* Always assume readable for a non-blocking read. We can't check FD_ISSET
+    /* Always assume readable for a non-blocking read. We can't check checked_fd_isset
        because we don't have a pcap_desc. */
     evmask |= EV_READ;
     return evmask;
@@ -352,11 +352,11 @@ static inline int get_evmask(const mspoo
 
   assert(sd >= 0);
 
-  if (FD_ISSET(sd, &sinfo->fds_results_r))
+  if (checked_fd_isset(sd, &sinfo->fds_results_r))
     evmask |= EV_READ;
-  if (FD_ISSET(sd, &sinfo->fds_results_w))
+  if (checked_fd_isset(sd, &sinfo->fds_results_w))
     evmask |= EV_WRITE;
-  if (FD_ISSET(sd, &sinfo->fds_results_x))
+  if (checked_fd_isset(sd, &sinfo->fds_results_x))
     evmask |= EV_EXCEPT;
 
   return evmask;
diff -up nmap-6.40/scan_engine.cc.fdsafe nmap-6.40/scan_engine.cc
--- nmap-6.40/scan_engine.cc.fdsafe	2013-07-29 00:08:48.000000000 +0200
+++ nmap-6.40/scan_engine.cc	2014-04-09 17:30:19.580033127 +0200
@@ -1006,10 +1006,10 @@ ConnectScanInfo::~ConnectScanInfo() {}
    watch an SD that was already being watched. */
 bool ConnectScanInfo::watchSD(int sd) {
   assert(sd >= 0);
-  if (!FD_ISSET(sd, &fds_read)) {
-    CHECKED_FD_SET(sd, &fds_read);
-    CHECKED_FD_SET(sd, &fds_write);
-    CHECKED_FD_SET(sd, &fds_except);
+  if (!checked_fd_isset(sd, &fds_read)) {
+    checked_fd_set(sd, &fds_read);
+    checked_fd_set(sd, &fds_write);
+    checked_fd_set(sd, &fds_except);
     numSDs++;
     if (sd > maxValidSD)
       maxValidSD = sd;
@@ -1024,10 +1024,10 @@ bool ConnectScanInfo::watchSD(int sd) {
    there in the first place. */
 bool ConnectScanInfo::clearSD(int sd) {
   assert(sd >= 0);
-  if (FD_ISSET(sd, &fds_read)) {
-    CHECKED_FD_CLR(sd, &fds_read);
-    CHECKED_FD_CLR(sd, &fds_write);
-    CHECKED_FD_CLR(sd, &fds_except);
+  if (checked_fd_isset(sd, &fds_read)) {
+    checked_fd_clr(sd, &fds_read);
+    checked_fd_clr(sd, &fds_write);
+    checked_fd_clr(sd, &fds_except);
     assert(numSDs > 0);
     numSDs--;
     if (sd == maxValidSD)
@@ -4096,8 +4096,9 @@ static bool do_one_select_round(UltraSca
       assert(probe->type == UltraProbe::UP_CONNECT);
       sd = probe->CP()->sd;
       /* Let see if anything has happened! */
-      if (sd >= 0 && (FD_ISSET(sd, &fds_rtmp)  || FD_ISSET(sd, &fds_wtmp) ||
-                      FD_ISSET(sd, &fds_xtmp))) {
+      if (sd >= 0 && (checked_fd_isset(sd, &fds_rtmp) ||
+                      checked_fd_isset(sd, &fds_wtmp) ||
+                      checked_fd_isset(sd, &fds_xtmp))) {
         numGoodSD++;
         newportstate = PORT_UNKNOWN;
         if (getsockopt(sd, SOL_SOCKET, SO_ERROR, (char *) &optval,