diff --git a/src/core/kernel/qcore_unix_p.h b/src/core/kernel/qcore_unix_p.h
index 095bdb966..b93d945ab 100644
--- a/src/core/kernel/qcore_unix_p.h
+++ b/src/core/kernel/qcore_unix_p.h
@@ -56,26 +56,6 @@
 #include <errno.h>
 #include <fcntl.h>
 
-struct sockaddr;
-
-#if defined(Q_OS_LINUX) && defined(O_CLOEXEC)
-# define QT_UNIX_SUPPORTS_THREADSAFE_CLOEXEC 1
-QT_BEGIN_NAMESPACE
-namespace QtLibcSupplement {
-    inline int accept4(int, sockaddr *, QT_SOCKLEN_T *, int)
-    { errno = ENOSYS; return -1; }
-    inline int dup3(int, int, int)
-    { errno = ENOSYS; return -1; }
-    inline int pipe2(int [], int )
-    { errno = ENOSYS; return -1; }
-}
-QT_END_NAMESPACE
-using namespace QT_PREPEND_NAMESPACE(QtLibcSupplement);
-
-#else
-# define QT_UNIX_SUPPORTS_THREADSAFE_CLOEXEC 0
-#endif
-
 #define EINTR_LOOP(var, cmd)                    \
     do {                                        \
         var = cmd;                              \
@@ -179,7 +159,7 @@ static inline int qt_safe_pipe(int pipefd[2], int flags = 0)
 #endif
 
     int ret;
-#if QT_UNIX_SUPPORTS_THREADSAFE_CLOEXEC && defined(O_CLOEXEC)
+#if defined(Q_OS_LINUX) && defined(O_CLOEXEC)
     // use pipe2
     flags |= O_CLOEXEC;
     ret = ::pipe2(pipefd, flags); // pipe2 is Linux-specific and is documented not to return EINTR
@@ -233,7 +213,7 @@ static inline int qt_safe_dup2(int oldfd, int newfd, int flags = FD_CLOEXEC)
     Q_ASSERT(flags == FD_CLOEXEC || flags == 0);
 
     int ret;
-#if QT_UNIX_SUPPORTS_THREADSAFE_CLOEXEC && defined(O_CLOEXEC)
+#if defined(Q_OS_LINUX) && defined(O_CLOEXEC)
     // use dup3
     if (flags & FD_CLOEXEC) {
         EINTR_LOOP(ret, ::dup3(oldfd, newfd, O_CLOEXEC));