diff --git a/nbase/nbase.h b/nbase/nbase.h
index ff795329c..078937fea 100644
--- a/nbase/nbase.h
+++ b/nbase/nbase.h
@@ -321,41 +321,37 @@ extern "C" int vsnprintf (char *, size_t, const char *, va_list);
 #define NORETURN
 #endif
 
+#ifndef WIN32
+# define CHECK_FD_OP(_Op) \
+  if (fd >= FD_SETSIZE) { \
+    fprintf(stderr, "Attempt to " #_Op " fd %d, which is not less than " \
+                    "FD_SETSIZE (%d). Try using a lower parallelism.", \
+                    fd, FD_SETSIZE); \
+    abort(); \
+  } \
+  return _Op(fd, fds);
+#else
+# define CHECK_FD_OP(_Op) return _Op(fd, fds);
+#endif
 
 static inline int checked_fd_isset(int fd, 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);
+  CHECK_FD_OP(FD_ISSET);
 }
 
 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);
+  CHECK_FD_OP(FD_CLR);
 }
 
 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 "
+#ifdef WIN32
+  if (fds->fd_count >= FD_SETSIZE) {
+    fprintf(stderr, "Attempt to call FD_SET, but fd_count is %d, which is not less than "
                     "FD_SETSIZE (%d). Try using a lower parallelism.",
-                    fd, FD_SETSIZE);
+                    fds->fd_count, FD_SETSIZE);
     abort();
   }
 #endif
-  FD_SET(fd, fds);
+  CHECK_FD_OP(FD_SET);
 }
 
 
diff --git a/nbase/nbase_misc.c b/nbase/nbase_misc.c
index b88cb4d16..8fb39280b 100644
--- a/nbase/nbase_misc.c
+++ b/nbase/nbase_misc.c
@@ -361,17 +361,17 @@ int fselect(int s, fd_set *rmaster, fd_set *wmaster, fd_set *emaster, struct tim
     int iter = -1, i;
     struct timeval stv;
     fd_set rset, wset, eset;
-    int r_stdin = rmaster != NULL && FD_ISSET(STDIN_FILENO, rmaster);
-    int e_stdin = emaster != NULL && FD_ISSET(STDIN_FILENO, emaster);
+    int r_stdin = rmaster != NULL && checked_fd_isset(STDIN_FILENO, rmaster);
+    int e_stdin = emaster != NULL && checked_fd_isset(STDIN_FILENO, emaster);
 
     /* Figure out whether there are any FDs in the sets, as @$@!$# Windows
        returns WSAINVAL (10022) if you call a select() with no FDs, even though
        the Linux man page says that doing so is a good, reasonably portable way
        to sleep with subsecond precision.  Sigh. */
     for(i = s; i > STDIN_FILENO; i--) {
-        if ((rmaster != NULL && FD_ISSET(i, rmaster))
-            || (wmaster != NULL && FD_ISSET(i, wmaster))
-            || (emaster != NULL && FD_ISSET(i, emaster)))
+        if ((rmaster != NULL && checked_fd_isset(i, rmaster))
+            || (wmaster != NULL && checked_fd_isset(i, wmaster))
+            || (emaster != NULL && checked_fd_isset(i, emaster)))
             break;
         s--;
     }
@@ -412,9 +412,9 @@ int fselect(int s, fd_set *rmaster, fd_set *wmaster, fd_set *emaster, struct tim
     }
 
     if (r_stdin)
-        FD_CLR(STDIN_FILENO, rmaster);
+        checked_fd_clr(STDIN_FILENO, rmaster);
     if (e_stdin)
-        FD_CLR(STDIN_FILENO, emaster);
+        checked_fd_clr(STDIN_FILENO, emaster);
 
     if (tv) {
         int usecs = (tv->tv_sec * 1000000) + tv->tv_usec;
@@ -448,7 +448,7 @@ int fselect(int s, fd_set *rmaster, fd_set *wmaster, fd_set *emaster, struct tim
             usleep(stv.tv_sec * 1000000UL + stv.tv_usec);
 
         if (fds_ready > -1 && r_stdin && win_stdin_ready()) {
-            FD_SET(STDIN_FILENO, &rset);
+            checked_fd_set(STDIN_FILENO, &rset);
             fds_ready++;
         }