diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp
index ae53dcdc328..8af38acf511 100644
--- a/src/corelib/plugin/qlibrary.cpp
+++ b/src/corelib/plugin/qlibrary.cpp
@@ -455,7 +455,7 @@ inline QLibraryPrivate *QLibraryStore::findOrCreate(const QString &fileName, con
         lib = new QLibraryPrivate(fileName, version, loadHints);
 
     // track this library
-    if (Q_LIKELY(data))
+    if (Q_LIKELY(data) && !fileName.isEmpty())
         data->libraryMap.insert(fileName, lib);
 
     lib->libraryRefCount.ref();
@@ -475,7 +475,7 @@ inline void QLibraryStore::releaseLibrary(QLibraryPrivate *lib)
     // no one else is using
     Q_ASSERT(lib->libraryUnloadCount.load() == 0);
 
-    if (Q_LIKELY(data)) {
+    if (Q_LIKELY(data) && !lib->fileName.isEmpty()) {
         QLibraryPrivate *that = data->libraryMap.take(lib->fileName);
         Q_ASSERT(lib == that);
         Q_UNUSED(that);
diff --git a/tests/auto/corelib/plugin/qlibrary/tst_qlibrary.cpp b/tests/auto/corelib/plugin/qlibrary/tst_qlibrary.cpp
index fc7e99103ca..2244f3e041c 100644
--- a/tests/auto/corelib/plugin/qlibrary/tst_qlibrary.cpp
+++ b/tests/auto/corelib/plugin/qlibrary/tst_qlibrary.cpp
@@ -456,6 +456,9 @@ void tst_QLibrary::loadHints()
     if (int(loadHints) != 0) {
         lh |= library.loadHints();
         library.setLoadHints(lh);
+
+        // confirm that another QLibrary doesn't get affected - QTBUG-39642
+        QCOMPARE(QLibrary().loadHints(), QLibrary::LoadHints());
     }
     library.setFileName(lib);
     QCOMPARE(library.loadHints(), lh);