diff --git a/src/bluetooth/qbluetoothdevicediscoveryagent.h b/src/bluetooth/qbluetoothdevicediscoveryagent.h
index 1641f16f07b71a91ea78cf0b792689d92ea9bbc1..81febdc435e8884cf8e6d33b614faf8c41b9f6ca 100644
--- a/src/bluetooth/qbluetoothdevicediscoveryagent.h
+++ b/src/bluetooth/qbluetoothdevicediscoveryagent.h
@@ -69,9 +69,9 @@ public:
     };
     Q_ENUM(InquiryType)
 
-    QBluetoothDeviceDiscoveryAgent(QObject *parent = 0);
+    explicit QBluetoothDeviceDiscoveryAgent(QObject *parent = Q_NULLPTR);
     explicit QBluetoothDeviceDiscoveryAgent(const QBluetoothAddress &deviceAdapter,
-                                            QObject *parent = 0);
+                                            QObject *parent = Q_NULLPTR);
     ~QBluetoothDeviceDiscoveryAgent();
 
     // TODO Remove inquiry type in Qt 6 -> not really used anywhere
diff --git a/src/bluetooth/qbluetoothdeviceinfo.h b/src/bluetooth/qbluetoothdeviceinfo.h
index e543286da50561432b184f689c614bb1a4f5e987..a39b593f05998616f38f3ae365b56cea37bb1c98 100644
--- a/src/bluetooth/qbluetoothdeviceinfo.h
+++ b/src/bluetooth/qbluetoothdeviceinfo.h
@@ -225,7 +225,7 @@ public:
     void setRssi(qint16 signal);
 
     void setServiceUuids(const QList<QBluetoothUuid> &uuids, DataCompleteness completeness);
-    QList<QBluetoothUuid> serviceUuids(DataCompleteness *completeness = 0) const;
+    QList<QBluetoothUuid> serviceUuids(DataCompleteness *completeness = Q_NULLPTR) const;
     DataCompleteness serviceUuidsCompleteness() const;
 
     void setCoreConfigurations(QBluetoothDeviceInfo::CoreConfigurations coreConfigs);
diff --git a/src/bluetooth/qbluetoothlocaldevice.h b/src/bluetooth/qbluetoothlocaldevice.h
index 40e143aba880a728506cb3930bc438d965849467..8d1d7b78f54a0a5379fab8cf6a9b6656e3622a50 100644
--- a/src/bluetooth/qbluetoothlocaldevice.h
+++ b/src/bluetooth/qbluetoothlocaldevice.h
@@ -73,8 +73,8 @@ public:
     };
     Q_ENUM(Error)
 
-    QBluetoothLocalDevice(QObject *parent = 0);
-    explicit QBluetoothLocalDevice(const QBluetoothAddress &address, QObject *parent = 0);
+    explicit QBluetoothLocalDevice(QObject *parent = Q_NULLPTR);
+    explicit QBluetoothLocalDevice(const QBluetoothAddress &address, QObject *parent = Q_NULLPTR);
     virtual ~QBluetoothLocalDevice();
 
     bool isValid() const;
diff --git a/src/bluetooth/qbluetoothserver.h b/src/bluetooth/qbluetoothserver.h
index 752780a5c871725ec63a53ab4a0ab98433bb01b2..47b0b88bad7ba85a7d5540a273d6977ee7b9e382 100644
--- a/src/bluetooth/qbluetoothserver.h
+++ b/src/bluetooth/qbluetoothserver.h
@@ -64,7 +64,7 @@ public:
     };
     Q_ENUM(Error)
 
-    QBluetoothServer(QBluetoothServiceInfo::Protocol serverType, QObject *parent = 0);
+    explicit QBluetoothServer(QBluetoothServiceInfo::Protocol serverType, QObject *parent = Q_NULLPTR);
     ~QBluetoothServer();
 
     void close();
diff --git a/src/bluetooth/qbluetoothservicediscoveryagent.h b/src/bluetooth/qbluetoothservicediscoveryagent.h
index 984a40841f48a0ae6ba4177c1c2c7bd38daf77d5..629259e4849c65c647c373895f19b518aa7c3e62 100644
--- a/src/bluetooth/qbluetoothservicediscoveryagent.h
+++ b/src/bluetooth/qbluetoothservicediscoveryagent.h
@@ -74,8 +74,8 @@ public:
     };
     Q_ENUM(DiscoveryMode)
 
-    QBluetoothServiceDiscoveryAgent(QObject *parent = 0);
-    explicit QBluetoothServiceDiscoveryAgent(const QBluetoothAddress &deviceAdapter, QObject *parent = 0);
+    explicit QBluetoothServiceDiscoveryAgent(QObject *parent = Q_NULLPTR);
+    explicit QBluetoothServiceDiscoveryAgent(const QBluetoothAddress &deviceAdapter, QObject *parent = Q_NULLPTR);
     ~QBluetoothServiceDiscoveryAgent();
 
     bool isActive() const;
diff --git a/src/bluetooth/qbluetoothsocket.h b/src/bluetooth/qbluetoothsocket.h
index 5d686d7f607c5b68aac0dd849b6cbc7b130e99ee..d5da783fa4c902fface15d66b809b9a3393a7c2d 100644
--- a/src/bluetooth/qbluetoothsocket.h
+++ b/src/bluetooth/qbluetoothsocket.h
@@ -82,8 +82,8 @@ public:
     };
     Q_ENUM(SocketError)
 
-    explicit QBluetoothSocket(QBluetoothServiceInfo::Protocol socketType, QObject *parent = 0);   // create socket of type socketType
-    QBluetoothSocket(QObject *parent = 0);  // create a blank socket
+    explicit QBluetoothSocket(QBluetoothServiceInfo::Protocol socketType, QObject *parent = Q_NULLPTR);   // create socket of type socketType
+    explicit QBluetoothSocket(QObject *parent = Q_NULLPTR);  // create a blank socket
     virtual ~QBluetoothSocket();
 
     void abort();
diff --git a/src/bluetooth/qbluetoothtransfermanager.h b/src/bluetooth/qbluetoothtransfermanager.h
index 6d6b03184f5535d52d9dcb8dece587d54a7a72a7..d4257fab9a8d2c501f81f51c3d97dd2abe582c7b 100644
--- a/src/bluetooth/qbluetoothtransfermanager.h
+++ b/src/bluetooth/qbluetoothtransfermanager.h
@@ -52,7 +52,7 @@ class Q_BLUETOOTH_EXPORT QBluetoothTransferManager : public QObject
     Q_OBJECT
 
 public:
-    explicit QBluetoothTransferManager(QObject *parent = 0);
+    explicit QBluetoothTransferManager(QObject *parent = Q_NULLPTR);
     ~QBluetoothTransferManager();
 
     QBluetoothTransferReply *put(const QBluetoothTransferRequest &request, QIODevice *data);
diff --git a/src/bluetooth/qbluetoothtransferreply.h b/src/bluetooth/qbluetoothtransferreply.h
index 755b9caa027c5afb4ee9ecb0b374caa71df8eb5f..3a5118b941e16b18f7f019c1d977e0b6807b1e34 100644
--- a/src/bluetooth/qbluetoothtransferreply.h
+++ b/src/bluetooth/qbluetoothtransferreply.h
@@ -82,7 +82,7 @@ Q_SIGNALS:
     void error(QBluetoothTransferReply::TransferError lastError);
 
 protected:
-    explicit QBluetoothTransferReply(QObject *parent = 0);
+    explicit QBluetoothTransferReply(QObject *parent = Q_NULLPTR);
     void setManager(QBluetoothTransferManager *manager);
     void setRequest(const QBluetoothTransferRequest &request);
 
diff --git a/src/bluetooth/qbluetoothuuid.h b/src/bluetooth/qbluetoothuuid.h
index 4646531c6daa8ac3deb63ae2dff39b02af6849bf..901d458faf969030e6916171822a278f54518666 100644
--- a/src/bluetooth/qbluetoothuuid.h
+++ b/src/bluetooth/qbluetoothuuid.h
@@ -376,8 +376,8 @@ public:
 
     int minimumSize() const;
 
-    quint16 toUInt16(bool *ok = 0) const;
-    quint32 toUInt32(bool *ok = 0) const;
+    quint16 toUInt16(bool *ok = Q_NULLPTR) const;
+    quint32 toUInt32(bool *ok = Q_NULLPTR) const;
     quint128 toUInt128() const;
 
     static QString serviceClassToString(ServiceClassUuid uuid);
diff --git a/src/bluetooth/qlowenergycontroller.h b/src/bluetooth/qlowenergycontroller.h
index be729dda1bb4993dbb3ead885445bd996d3e9238..27e88ded480193c1ec869283f06917e3ba872ace 100644
--- a/src/bluetooth/qlowenergycontroller.h
+++ b/src/bluetooth/qlowenergycontroller.h
@@ -74,12 +74,12 @@ public:
     Q_ENUM(RemoteAddressType)
 
     explicit QLowEnergyController(const QBluetoothAddress &remoteDevice,
-                                     QObject *parent = 0); // TODO Qt 6 remove ctor
+                                  QObject *parent = Q_NULLPTR); // TODO Qt 6 remove ctor
     explicit QLowEnergyController(const QBluetoothDeviceInfo &remoteDevice,
-                                     QObject *parent = 0);
+                                  QObject *parent = Q_NULLPTR);
     explicit QLowEnergyController(const QBluetoothAddress &remoteDevice,
                                      const QBluetoothAddress &localDevice,
-                                     QObject *parent = 0); // TODO Qt 6 remove ctor
+                                  QObject *parent = Q_NULLPTR); // TODO Qt 6 remove ctor
     ~QLowEnergyController();
 
     QBluetoothAddress localAddress() const;
@@ -97,8 +97,7 @@ public:
 
     void discoverServices();
     QList<QBluetoothUuid> services() const;
-    QLowEnergyService *createServiceObject(
-            const QBluetoothUuid &service, QObject *parent = 0);
+    QLowEnergyService *createServiceObject(const QBluetoothUuid &service, QObject *parent = Q_NULLPTR);
 
     Error error() const;
     QString errorString() const;
diff --git a/src/bluetooth/qlowenergyservice.h b/src/bluetooth/qlowenergyservice.h
index 524650c975fa9f91da37b8211470b645eea932db..767bf6d68ad9a8f90606365bc00925f1072a89a0 100644
--- a/src/bluetooth/qlowenergyservice.h
+++ b/src/bluetooth/qlowenergyservice.h
@@ -127,7 +127,7 @@ private:
     // QLowEnergyController is the factory for this class
     friend class QLowEnergyController;
     QLowEnergyService(QSharedPointer<QLowEnergyServicePrivate> p,
-                      QObject *parent = 0);
+                      QObject *parent = Q_NULLPTR);
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(QLowEnergyService::ServiceTypes)
diff --git a/src/nfc/qnearfieldmanager.h b/src/nfc/qnearfieldmanager.h
index 416c5e9109d81bd425067cc9b3aee582de5644ba..8c91a8010019da5693a014b9e9b4c1c9ae924efe 100644
--- a/src/nfc/qnearfieldmanager.h
+++ b/src/nfc/qnearfieldmanager.h
@@ -59,8 +59,8 @@ public:
     Q_ENUM(TargetAccessMode)
     Q_DECLARE_FLAGS(TargetAccessModes, TargetAccessMode)
 
-    explicit QNearFieldManager(QObject *parent = 0);
-    explicit QNearFieldManager(QNearFieldManagerPrivate *backend, QObject *parent = 0);
+    explicit QNearFieldManager(QObject *parent = Q_NULLPTR);
+    explicit QNearFieldManager(QNearFieldManagerPrivate *backend, QObject *parent = Q_NULLPTR);
     ~QNearFieldManager();
 
     bool isAvailable() const;
diff --git a/src/nfc/qnearfieldsharemanager.h b/src/nfc/qnearfieldsharemanager.h
index 264e82b606d3d1efbb618df39b86b9e71a69575a..03dc4db9f131d49ab7389cd16826f8645200a6f4 100644
--- a/src/nfc/qnearfieldsharemanager.h
+++ b/src/nfc/qnearfieldsharemanager.h
@@ -47,7 +47,7 @@ class Q_NFC_EXPORT QNearFieldShareManager : public QObject
     Q_OBJECT
 
 public:
-    explicit QNearFieldShareManager(QObject *parent = 0);
+    explicit QNearFieldShareManager(QObject *parent = Q_NULLPTR);
     ~QNearFieldShareManager();
 
     enum ShareError {
diff --git a/src/nfc/qnearfieldsharetarget.h b/src/nfc/qnearfieldsharetarget.h
index cc85086f9f5526e6c66fb22081c9a848a2b0a8c8..36f4a5cc51af01ccba9774f0b9a5052b4d75031b 100644
--- a/src/nfc/qnearfieldsharetarget.h
+++ b/src/nfc/qnearfieldsharetarget.h
@@ -63,7 +63,7 @@ Q_SIGNALS:
     void shareFinished();
 
 private:
-    explicit QNearFieldShareTarget(QNearFieldShareManager::ShareModes modes, QObject *parent = 0);
+    explicit QNearFieldShareTarget(QNearFieldShareManager::ShareModes modes, QObject *parent = Q_NULLPTR);
 
     QNearFieldShareTargetPrivate *d_ptr;
     Q_DECLARE_PRIVATE(QNearFieldShareTarget)
diff --git a/src/nfc/qnearfieldtarget.h b/src/nfc/qnearfieldtarget.h
index a7abbe25be9b11278334e691be699cf1018442b0..d9f6786ef2000e72a6f98cb631fb11303dea260b 100644
--- a/src/nfc/qnearfieldtarget.h
+++ b/src/nfc/qnearfieldtarget.h
@@ -110,7 +110,7 @@ public:
         QSharedDataPointer<RequestIdPrivate> d;
     };
 
-    explicit QNearFieldTarget(QObject *parent = 0);
+    explicit QNearFieldTarget(QObject *parent = Q_NULLPTR);
     virtual ~QNearFieldTarget();
 
     virtual QByteArray uid() const = 0;
diff --git a/src/nfc/qqmlndefrecord.h b/src/nfc/qqmlndefrecord.h
index 93a3106e190faa8720af6abe3ce0e460b1b06973..35b2ab5fb06e4ce38aa064559c45a1f5daf6dbb2 100644
--- a/src/nfc/qqmlndefrecord.h
+++ b/src/nfc/qqmlndefrecord.h
@@ -63,8 +63,8 @@ public:
     };
     Q_ENUM(TypeNameFormat)
 
-    explicit QQmlNdefRecord(QObject *parent = 0);
-    explicit QQmlNdefRecord(const QNdefRecord &record, QObject *parent = 0);
+    explicit QQmlNdefRecord(QObject *parent = Q_NULLPTR);
+    explicit QQmlNdefRecord(const QNdefRecord &record, QObject *parent = Q_NULLPTR);
     ~QQmlNdefRecord();
 
     QString type() const;