3 files changed, 7 insertions, 2 deletions
diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp
index ddb053c26f..be9d92b204 100644
--- a/src/corelib/plugin/qlibrary.cpp
+++ b/src/corelib/plugin/qlibrary.cpp
@@ -576,9 +576,7 @@ bool QLibraryPrivate::load()
 
     Q_TRACE(QLibraryPrivate_load_entry, fileName);
 
-    mutex.lock();
     bool ret = load_sys();
-    mutex.unlock();
     if (qt_debug_component()) {
         if (ret) {
             qDebug() << "loaded library" << fileName;
diff --git a/src/corelib/plugin/qlibrary_unix.cpp b/src/corelib/plugin/qlibrary_unix.cpp
index 017aa97b66..a5c72f81d9 100644
--- a/src/corelib/plugin/qlibrary_unix.cpp
+++ b/src/corelib/plugin/qlibrary_unix.cpp
@@ -123,6 +123,7 @@ QStringList QLibraryPrivate::prefixes_sys()
 
 bool QLibraryPrivate::load_sys()
 {
+    QMutexLocker locker(&mutex);
     QString attempt;
     QFileSystemEntry fsEntry(fileName);
 
@@ -213,6 +214,7 @@ bool QLibraryPrivate::load_sys()
     }
 #endif
 
+    locker.unlock();
     bool retry = true;
     Handle hnd = nullptr;
     for (int prefix = 0; retry && !hnd && prefix < prefixes.size(); prefix++) {
@@ -273,6 +275,8 @@ bool QLibraryPrivate::load_sys()
         }
     }
 #endif
+
+    locker.relock();
     if (!hnd) {
         errorString = QLibrary::tr("Cannot load library %1: %2").arg(fileName, qdlerror());
     }
diff --git a/src/corelib/plugin/qlibrary_win.cpp b/src/corelib/plugin/qlibrary_win.cpp
index 000bf76276..ef58724be8 100644
--- a/src/corelib/plugin/qlibrary_win.cpp
+++ b/src/corelib/plugin/qlibrary_win.cpp
@@ -78,6 +78,7 @@ bool QLibraryPrivate::load_sys()
     //     fileName
     //
     // NB If it's a plugin we do not ever try the ".dll" extension
+    QMutexLocker locker(&mutex);
     QStringList attempts;
 
     if (pluginState != IsAPlugin)
@@ -95,6 +96,7 @@ bool QLibraryPrivate::load_sys()
         attempts.prepend(QDir::rootPath() + fileName);
 #endif
 
+    locker.unlock();
     Handle hnd = nullptr;
     for (const QString &attempt : qAsConst(attempts)) {
 #ifndef Q_OS_WINRT
@@ -115,6 +117,7 @@ bool QLibraryPrivate::load_sys()
 #ifndef Q_OS_WINRT
     SetErrorMode(oldmode);
 #endif
+    locker.relock();
     if (!hnd) {
         errorString = QLibrary::tr("Cannot load library %1: %2").arg(
                     QDir::toNativeSeparators(fileName), qt_error_string());