diff --git a/src/kpackage/package.cpp b/src/kpackage/package.cpp
--- a/src/kpackage/package.cpp
+++ b/src/kpackage/package.cpp
@@ -376,7 +376,7 @@
             QString file = prefix + path;
 
             if (!filename.isEmpty()) {
-                file = file + QLatin1Char('/') + filename;
+                file.append(QLatin1Char('/') + filename);
             }
 
             QFileInfo fi(file);
diff --git a/src/kpackage/packageloader.cpp b/src/kpackage/packageloader.cpp
--- a/src/kpackage/packageloader.cpp
+++ b/src/kpackage/packageloader.cpp
@@ -172,9 +172,11 @@
         useRuntimeCache = false;
         d->pluginCache.clear();
     }
-    QString cacheKey = QString(QStringLiteral("%1.%2")).arg(packageFormat, packageRoot);
-    if (useRuntimeCache && d->pluginCache.contains(cacheKey)) {
-        return d->pluginCache.value(cacheKey);
+    if (useRuntimeCache) {
+        auto it = d->pluginCache.constFind(QStringLiteral("%1.%2").arg(packageFormat, packageRoot));
+        if (it != d->pluginCache.constEnd()) {
+            return *it;
+        }
     }
     if (d->pluginCacheAge == 0) {
         d->pluginCacheAge = now;