diff --git a/src/gsttools/qgstutils.cpp b/src/gsttools/qgstutils.cpp
index ac880811559e967d762e720b2970579fdc91105c..f8a9d79c1fc3803b130512f5f2625d8636644d1d 100644
--- a/src/gsttools/qgstutils.cpp
+++ b/src/gsttools/qgstutils.cpp
@@ -1309,7 +1309,7 @@ void QGstUtils::setMetaData(GstElement *element, const QMap<QByteArray, QVariant
 
     for (auto it = data.cbegin(), end = data.cend(); it != end; ++it) {
         const QString tagName = QString::fromLatin1(it.key());
-        const QVariant tagValue = it.value();
+        const QVariant &tagValue = it.value();
 
         switch (tagValue.type()) {
             case QVariant::String:
diff --git a/src/plugins/alsa/qalsaaudiodeviceinfo.cpp b/src/plugins/alsa/qalsaaudiodeviceinfo.cpp
index 5e8edc3fc9689ae725ffa5d4fd50f27bfebf2192..474fd6bdeb698880e90936b7a7cecc4930574e0f 100644
--- a/src/plugins/alsa/qalsaaudiodeviceinfo.cpp
+++ b/src/plugins/alsa/qalsaaudiodeviceinfo.cpp
@@ -54,7 +54,7 @@
 
 QT_BEGIN_NAMESPACE
 
-QAlsaAudioDeviceInfo::QAlsaAudioDeviceInfo(QByteArray dev, QAudio::Mode mode)
+QAlsaAudioDeviceInfo::QAlsaAudioDeviceInfo(const QByteArray &dev, QAudio::Mode mode)
 {
     handle = 0;
 
diff --git a/src/plugins/alsa/qalsaaudiodeviceinfo.h b/src/plugins/alsa/qalsaaudiodeviceinfo.h
index 21e30f49bce511ec40f982d49c83d0b9219f39d2..65675df547bce52a6566f5d727b4a7c5a3e95968 100644
--- a/src/plugins/alsa/qalsaaudiodeviceinfo.h
+++ b/src/plugins/alsa/qalsaaudiodeviceinfo.h
@@ -74,7 +74,7 @@ class QAlsaAudioDeviceInfo : public QAbstractAudioDeviceInfo
 {
     Q_OBJECT
 public:
-    QAlsaAudioDeviceInfo(QByteArray dev,QAudio::Mode mode);
+    QAlsaAudioDeviceInfo(const QByteArray &dev,QAudio::Mode mode);
     ~QAlsaAudioDeviceInfo();
 
     bool testSettings(const QAudioFormat& format) const;
diff --git a/src/plugins/gstreamer/mediacapture/qgstreameraudioencode.cpp b/src/plugins/gstreamer/mediacapture/qgstreameraudioencode.cpp
index 98aaded7219434e267e516bf41755feefcbc053b..1a35c5cf6dc1015a3aa6b9483235ccf57c696120 100644
--- a/src/plugins/gstreamer/mediacapture/qgstreameraudioencode.cpp
+++ b/src/plugins/gstreamer/mediacapture/qgstreameraudioencode.cpp
@@ -205,8 +205,8 @@ GstElement *QGstreamerAudioEncode::createEncoder()
 
         QMap<QString, QVariant> options = m_options.value(codec);
         for (auto it = options.cbegin(), end = options.cend(); it != end; ++it) {
-            QString option = it.key();
-            QVariant value = it.value();
+            const QString &option = it.key();
+            const QVariant &value = it.value();
 
             switch (value.type()) {
             case QVariant::Int:
diff --git a/src/plugins/gstreamer/mediacapture/qgstreamervideoencode.cpp b/src/plugins/gstreamer/mediacapture/qgstreamervideoencode.cpp
index 4cc0e5f2576ee45e58e5b92efa23864b63069f0a..a2ed1d288bbf6eebdb427bc3800ffa7a1be3db41 100644
--- a/src/plugins/gstreamer/mediacapture/qgstreamervideoencode.cpp
+++ b/src/plugins/gstreamer/mediacapture/qgstreamervideoencode.cpp
@@ -196,8 +196,8 @@ GstElement *QGstreamerVideoEncode::createEncoder()
 
         QMap<QString,QVariant> options = m_options.value(codec);
         for (auto it = options.cbegin(), end = options.cend(); it != end; ++it) {
-            QString option = it.key();
-            QVariant value = it.value();
+            const QString &option = it.key();
+            const QVariant &value = it.value();
 
             switch (value.type()) {
             case QVariant::Int: