3 files changed, 5 insertions, 2 deletions
diff --git a/src/corelib/io/qlockfile.cpp b/src/corelib/io/qlockfile.cpp
index cb1ff93ad3..48317d07e0 100644
--- a/src/corelib/io/qlockfile.cpp
+++ b/src/corelib/io/qlockfile.cpp
@@ -44,6 +44,7 @@
 #include <QtCore/qthread.h>
 #include <QtCore/qdeadlinetimer.h>
 #include <QtCore/qdatetime.h>
+#include <QtCore/qfileinfo.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -226,6 +227,8 @@ bool QLockFile::tryLock(int timeout)
             return false;
         case LockFailedError:
             if (!d->isLocked && d->isApparentlyStale()) {
+                if (Q_UNLIKELY(QFileInfo(d->fileName).lastModified() > QDateTime::currentDateTime()))
+                    qInfo("QLockFile: Lock file '%ls' has a modification time in the future", qUtf16Printable(d->fileName));
                 // Stale lock from another thread/process
                 // Ensure two processes don't remove it at the same time
                 QLockFile rmlock(d->fileName + QLatin1String(".rmlock"));
diff --git a/src/corelib/io/qlockfile_unix.cpp b/src/corelib/io/qlockfile_unix.cpp
index 3a80014c00..5a02741727 100644
--- a/src/corelib/io/qlockfile_unix.cpp
+++ b/src/corelib/io/qlockfile_unix.cpp
@@ -247,7 +247,7 @@ bool QLockFilePrivate::isApparentlyStale() const
         }
     }
     const qint64 age = QFileInfo(fileName).lastModified().msecsTo(QDateTime::currentDateTime());
-    return staleLockTime > 0 && age > staleLockTime;
+    return staleLockTime > 0 && qAbs(age) > staleLockTime;
 }
 
 QString QLockFilePrivate::processNameByPid(qint64 pid)
diff --git a/src/corelib/io/qlockfile_win.cpp b/src/corelib/io/qlockfile_win.cpp
index baaff8da17..4b43181686 100644
--- a/src/corelib/io/qlockfile_win.cpp
+++ b/src/corelib/io/qlockfile_win.cpp
@@ -160,7 +160,7 @@ bool QLockFilePrivate::isApparentlyStale() const
     Q_UNUSED(appname);
 #endif // Q_OS_WINRT
     const qint64 age = QFileInfo(fileName).lastModified().msecsTo(QDateTime::currentDateTime());
-    return staleLockTime > 0 && age > staleLockTime;
+    return staleLockTime > 0 && qAbs(age) > staleLockTime;
 }
 
 QString QLockFilePrivate::processNameByPid(qint64 pid)