diff --git a/src/widgets/previewjob.cpp b/src/widgets/previewjob.cpp
--- a/src/widgets/previewjob.cpp
+++ b/src/widgets/previewjob.cpp
@@ -415,8 +415,6 @@
 void PreviewJobPrivate::cleanupTempFile()
 {
     if (!tempName.isEmpty()) {
-        Q_ASSERT(!QFileInfo(tempName).isDir());
-        Q_ASSERT(QFileInfo(tempName).isFile());
         QFile::remove(tempName);
         tempName.clear();
     }
@@ -610,7 +608,7 @@
         // No plugin support access to this remote content, copy the file
         // to the local machine, then create the thumbnail
         state = PreviewJobPrivate::STATE_GETORIG;
-        QTemporaryFile localFile;
+        QTemporaryFile localFile(QStringLiteral("thumbnailXXXXXX"));
         localFile.setAutoRemove(false);
         localFile.open();
         tempName = localFile.fileName();