diff --git a/src/corelib/io/qlockfile_unix.cpp b/src/corelib/io/qlockfile_unix.cpp
index ccc607afd5..f21aced87c 100644
--- a/src/corelib/io/qlockfile_unix.cpp
+++ b/src/corelib/io/qlockfile_unix.cpp
@@ -199,7 +199,7 @@ QLockFile::LockError QLockFilePrivate::tryLock_sys()
     }
 
     if (qt_write_loop(fd, fileData.constData(), fileData.size()) < fileData.size()) {
-        close(fd);
+        qt_safe_close(fd);
         if (!QFile::remove(fileName))
             qWarning("QLockFile: Could not remove our own lock file %s.", qPrintable(fileName));
         return QLockFile::UnknownError; // partition full
@@ -258,7 +258,7 @@ QString QLockFilePrivate::processNameByPid(qint64 pid)
     proc_name(pid, name, sizeof(name) / sizeof(char));
     return QFile::decodeName(name);
 #elif defined(Q_OS_LINUX)
-    if (!QFile::exists(QStringLiteral("/proc/version")))
+    if (!qt_haveLinuxProcfs())
         return QString();
     char exePath[64];
     char buf[PATH_MAX + 1];
diff --git a/src/corelib/kernel/qcore_unix_p.h b/src/corelib/kernel/qcore_unix_p.h
index eca575ba01..ea5d98cbf3 100644
--- a/src/corelib/kernel/qcore_unix_p.h
+++ b/src/corelib/kernel/qcore_unix_p.h
@@ -340,6 +340,21 @@ static inline pid_t qt_safe_waitpid(pid_t pid, int *status, int options)
 timespec qt_gettime() Q_DECL_NOTHROW;
 void qt_nanosleep(timespec amount);
 
+/* non-static */
+inline bool qt_haveLinuxProcfs()
+{
+#ifdef Q_OS_LINUX
+#  ifdef QT_LINUX_ALWAYS_HAVE_PROCFS
+    return true;
+#  else
+    static const bool present = (access("/proc/version", F_OK) == 0);
+    return present;
+#  endif
+#else
+    return false;
+#endif
+}
+
 Q_CORE_EXPORT int qt_safe_poll(struct pollfd *fds, nfds_t nfds, const struct timespec *timeout_ts);
 
 static inline int qt_poll_msecs(struct pollfd *fds, nfds_t nfds, int timeout)