diff --git a/src/core/kexipartmanager.cpp b/src/core/kexipartmanager.cpp
--- a/src/core/kexipartmanager.cpp
+++ b/src/core/kexipartmanager.cpp
@@ -167,8 +167,8 @@
     QStringList serviceTypes;
     serviceTypes << "Kexi/Viewer" << "Kexi/Designer" << "Kexi/Editor"
                  << "Kexi/ModalDialog";
-    const QList<QPluginLoader*> offers = KexiPartTrader_instance->query(serviceTypes);
-    foreach(QPluginLoader *loader, offers) {
+    QList<QPluginLoader*> offers = KexiPartTrader_instance->query(serviceTypes);
+    foreach(const QPluginLoader *loader, offers) {
         QScopedPointer<Info> info(new Info(*loader));
         if (info->id().isEmpty()) {
             qWarning() << "No plugin ID (X-KDE-PluginInfo-Name) specified for Kexi Part"
@@ -213,6 +213,8 @@
         d->partsByPluginId.insert(info->pluginId(), info.data());
         info.take();
     }
+    qDeleteAll(offers);
+    offers.clear();
 
     // fill the final list using computed order
     for (int i = 0; i < orderedInfos.size(); i++) {
diff --git a/src/formeditor/widgetlibrary.cpp b/src/formeditor/widgetlibrary.cpp
--- a/src/formeditor/widgetlibrary.cpp
+++ b/src/formeditor/widgetlibrary.cpp
@@ -138,7 +138,7 @@
 
         QStringList serviceTypes;
         serviceTypes << "Kexi/FormWidgets";
-        const QList<QPluginLoader*> offers = KexiFormWidgetsPluginTrader_instance->query(serviceTypes);
+        QList<QPluginLoader*> offers = KexiFormWidgetsPluginTrader_instance->query(serviceTypes);
         foreach(const QPluginLoader *loader, offers) {
             QScopedPointer<KexiFormWidgetsPluginMetaData> metaData(new KexiFormWidgetsPluginMetaData(*loader));
             if (metaData->id().isEmpty()) {
@@ -172,6 +172,8 @@
             m_pluginsMetaData.insert(metaData->id(), metaData.data());
             metaData.take();
         }
+        qDeleteAll(offers);
+        offers.clear();
         if (m_pluginsMetaData.isEmpty()) {
             q->m_result = KDbResult(i18n("Could not find any form widget plugins."));
             m_couldNotFindAnyFormWidgetPluginsErrorDisplayed = true;
diff --git a/src/kexiutils/KexiJsonTrader.h b/src/kexiutils/KexiJsonTrader.h
--- a/src/kexiutils/KexiJsonTrader.h
+++ b/src/kexiutils/KexiJsonTrader.h
@@ -60,6 +60,8 @@
      *
      * @return A list of QPluginLoader that satisfy the query
      * @see http://techbase.kde.org/Development/Tutorials/Services/Traders#The_KTrader_Query_Language
+     *
+     * @note Ownership of the QPluginLoader objects is transferred to the caller.
      */
      QList<QPluginLoader *> query(const QStringList &servicetypes, const QString &mimetype = QString());
 
diff --git a/src/kexiutils/KexiJsonTrader.cpp b/src/kexiutils/KexiJsonTrader.cpp
--- a/src/kexiutils/KexiJsonTrader.cpp
+++ b/src/kexiutils/KexiJsonTrader.cpp
@@ -84,6 +84,38 @@
     return json.value(QLatin1String("KPlugin")).toObject();
 }
 
+//! Checks loader @a loader
+static bool checkLoader(QPluginLoader *loader, const QStringList &servicetypes,
+                        const QString &mimetype)
+{
+    const QJsonObject pluginData = KexiJsonTrader::rootObjectForPluginLoader(*loader);
+    if (pluginData.isEmpty()) {
+        //qDebug() << dirIter.filePath() << "has no json!";
+        return false;
+    }
+    const QJsonArray foundServiceTypesAray = pluginData.value(QLatin1String("ServiceTypes")).toArray();
+    if (foundServiceTypesAray.isEmpty()) {
+        qWarning() << "No ServiceTypes defined for plugin" << loader->fileName() << "-- skipping!";
+        return false;
+    }
+    QStringList foundServiceTypes = KexiUtils::convertTypesUsingMethod<QVariant, QString, &QVariant::toString>(foundServiceTypesAray.toVariantList());
+    if (!supportsAtLeastServiceType(foundServiceTypes, servicetypes)) {
+        return false;
+    }
+
+    if (!mimetype.isEmpty()) {
+        QJsonObject json = metaDataObjectForPluginLoader(*loader);
+        QStringList mimeTypes = json.value(QLatin1String("X-KDE-ExtraNativeMimeTypes"))
+                .toString().split(QLatin1Char(','));
+        mimeTypes += json.value(QLatin1String("MimeType")).toString().split(QLatin1Char(';'));
+        mimeTypes += json.value(QLatin1String("X-KDE-NativeMimeType")).toString();
+        if (! mimeTypes.contains(mimetype)) {
+            return false;
+        }
+    }
+    return true;
+}
+
 static QList<QPluginLoader *> findPlugins(const QString &path, const QStringList &servicetypes,
                                           const QString &mimetype)
 {
@@ -93,32 +125,11 @@
         dirIter.next();
         if (dirIter.fileInfo().isFile()) {
             QPluginLoader *loader = new QPluginLoader(dirIter.filePath());
-            const QJsonObject pluginData = KexiJsonTrader::rootObjectForPluginLoader(*loader);
-            if (pluginData.isEmpty()) {
-                //qDebug() << dirIter.filePath() << "has no json!";
-                continue;
-            }
-            const QJsonArray foundServiceTypesAray = pluginData.value(QLatin1String("ServiceTypes")).toArray();
-            if (foundServiceTypesAray.isEmpty()) {
-                qWarning() << "No ServiceTypes defined for plugin" << loader->fileName() << "-- skipping!";
-                continue;
-            }
-            QStringList foundServiceTypes = KexiUtils::convertTypesUsingMethod<QVariant, QString, &QVariant::toString>(foundServiceTypesAray.toVariantList());
-            if (!supportsAtLeastServiceType(foundServiceTypes, servicetypes)) {
-                continue;
-            }
-
-            if (!mimetype.isEmpty()) {
-                QJsonObject json = metaDataObjectForPluginLoader(*loader);
-                QStringList mimeTypes = json.value(QLatin1String("X-KDE-ExtraNativeMimeTypes"))
-                        .toString().split(QLatin1Char(','));
-                mimeTypes += json.value(QLatin1String("MimeType")).toString().split(QLatin1Char(';'));
-                mimeTypes += json.value(QLatin1String("X-KDE-NativeMimeType")).toString();
-                if (! mimeTypes.contains(mimetype)) {
-                    continue;
-                }
+            if (checkLoader(loader, servicetypes, mimetype)) {
+                list.append(loader);
+            } else {
+                delete loader;
             }
-            list.append(loader);
         }
     }
     return list;