diff --git a/src/backends/libinput/device.cpp b/src/backends/libinput/device.cpp
index 12647429b6..342a2b9d0a 100644
--- a/src/backends/libinput/device.cpp
+++ b/src/backends/libinput/device.cpp
@@ -121,7 +121,7 @@ struct ConfigData {
         : key(_key)
     { quint32Setter.setter = _setter; quint32Setter.defaultValue = _defaultValue; }
 
-    explicit ConfigData(QByteArray _key, void (Device::*_setter)(QString), QString (Device::*_defaultValue)() const = nullptr)
+    explicit ConfigData(QByteArray _key, void (Device::*_setter)(const QString&), QString (Device::*_defaultValue)() const = nullptr)
         : key(_key)
     { stringSetter.setter = _setter; stringSetter.defaultValue = _defaultValue; }
 
@@ -153,7 +153,7 @@ struct ConfigData {
         quint32 (Device::*defaultValue)() const;
     } quint32Setter;
     struct {
-        void (Device::*setter)(QString) = nullptr;
+        void (Device::*setter)(const QString&) = nullptr;
         QString (Device::*defaultValue)() const;
     } stringSetter;
     struct {
@@ -660,7 +660,7 @@ void Device::setOrientation(Qt::ScreenOrientation orientation)
     }
 }
 
-void Device::setOutputName(QString name)
+void Device::setOutputName(const QString &name)
 {
 #ifndef KWIN_BUILD_TESTING
     if (name.isEmpty()) {
diff --git a/src/backends/libinput/device.h b/src/backends/libinput/device.h
index 251733086b..ce6e58b84b 100644
--- a/src/backends/libinput/device.h
+++ b/src/backends/libinput/device.h
@@ -384,7 +384,7 @@ public:
      * @param acceleration mapped to range [-1,1] with -1 being the slowest, 1 being the fastest supported acceleration.
      */
     void setPointerAcceleration(qreal acceleration);
-    void setPointerAccelerationFromString(QString acceleration) {
+    void setPointerAccelerationFromString(const QString &acceleration) {
         setPointerAcceleration(acceleration.toDouble());
     }
     QString defaultPointerAccelerationToString() const {
@@ -473,7 +473,7 @@ public:
     /**
      * Used to deserialize monitor data from KConfig when initializing a device
      */
-    void setOutputName(QString uuid);
+    void setOutputName(const QString &uuid);
     QString defaultOutputName() const
     {
         return {};