diff --git a/src/file/fileindexerconfig.cpp b/src/file/fileindexerconfig.cpp
--- a/src/file/fileindexerconfig.cpp
+++ b/src/file/fileindexerconfig.cpp
@@ -107,28 +107,33 @@
     KConfigGroup cfg = m_config.group("General");
 
     // read configured exclude filters
-    QSet<QString> filters = cfg.readEntry("exclude filters", defaultExcludeFilterList()).toSet();
+    QStringList filters = cfg.readEntry("exclude filters", defaultExcludeFilterList());
 
     // make sure we always keep the latest default exclude filters
     // TODO: there is one problem here. What if the user removed some of the default filters?
     if (cfg.readEntry("exclude filters version", 0) < defaultExcludeFilterListVersion()) {
-        filters += defaultExcludeFilterList().toSet();
+        filters += defaultExcludeFilterList();
+        // in case the cfg entry was empty and filters == defaultExcludeFilterList()
+        filters.removeDuplicates();
 
         // write the config directly since the KCM does not have support for the version yet
         // TODO: make this class public and use it in the KCM
         KConfig config(m_config.name());
         KConfigGroup cfg = config.group("General");
-        cfg.writeEntry("exclude filters", QStringList::fromSet(filters));
+        cfg.writeEntry("exclude filters", filters);
         cfg.writeEntry("exclude filters version", defaultExcludeFilterListVersion());
     }
 
-    // remove duplicates
-    return QStringList::fromSet(filters);
+    return filters;
 }
 
 QStringList FileIndexerConfig::excludeMimetypes() const
 {
+#if QT_VERSION < QT_VERSION_CHECK(5, 14, 0)
     return QStringList::fromSet(m_excludeMimetypes);
+#else
+    return QList<QString>(m_excludeMimetypes.begin(), m_excludeMimetypes.end());
+#endif
 }
 
 bool FileIndexerConfig::indexHiddenFilesAndFolders() const
@@ -350,7 +355,12 @@
 
 void FileIndexerConfig::buildMimeTypeCache()
 {
-    m_excludeMimetypes = m_config.group("General").readPathEntry("exclude mimetypes", defaultExcludeMimetypes()).toSet();
+    const QStringList excludedTypes = m_config.group("General").readPathEntry("exclude mimetypes", defaultExcludeMimetypes());
+#if QT_VERSION < QT_VERSION_CHECK(5, 14, 0)
+    m_excludeMimetypes = excludedTypes.toSet();
+#else
+    m_excludeMimetypes = QSet<QString>(excludedTypes.begin(), excludedTypes.end());
+#endif
 }
 
 void FileIndexerConfig::forceConfigUpdate()
diff --git a/src/lib/filemonitor.cpp b/src/lib/filemonitor.cpp
--- a/src/lib/filemonitor.cpp
+++ b/src/lib/filemonitor.cpp
@@ -64,12 +64,20 @@
 
 void FileMonitor::setFiles(const QStringList& fileList)
 {
+#if QT_VERSION < QT_VERSION_CHECK(5, 14, 0)
     d->m_files = fileList.toSet();
+#else
+    d->m_files = QSet<QString>(fileList.begin(), fileList.end());
+#endif
 }
 
 QStringList FileMonitor::files() const
 {
+#if QT_VERSION < QT_VERSION_CHECK(5, 14, 0)
     return QStringList(d->m_files.toList());
+#else
+    return QList<QString>(d->m_files.begin(), d->m_files.end());
+#endif
 }
 
 void FileMonitor::clear()