diff --git a/src/lib/code39barcode.cpp b/src/lib/code39barcode.cpp
--- a/src/lib/code39barcode.cpp
+++ b/src/lib/code39barcode.cpp
@@ -96,7 +96,7 @@
 @endcond
 */
 
-Code39Barcode::Code39Barcode() : AbstractBarcode(), d(0){
+Code39Barcode::Code39Barcode() : AbstractBarcode(), d(nullptr){
 }
 
 Code39Barcode::~Code39Barcode() {
diff --git a/src/lib/code93barcode.cpp b/src/lib/code93barcode.cpp
--- a/src/lib/code93barcode.cpp
+++ b/src/lib/code93barcode.cpp
@@ -250,7 +250,7 @@
 @endcond
 */
 
-Code93Barcode::Code93Barcode() : AbstractBarcode(), d(0){
+Code93Barcode::Code93Barcode() : AbstractBarcode(), d(nullptr){
 }
 
 Code93Barcode::~Code93Barcode() {
diff --git a/src/lib/datamatrixbarcode.cpp b/src/lib/datamatrixbarcode.cpp
--- a/src/lib/datamatrixbarcode.cpp
+++ b/src/lib/datamatrixbarcode.cpp
@@ -39,7 +39,7 @@
  * @endcond
  */
 
-DataMatrixBarcode::DataMatrixBarcode() : d(0) {
+DataMatrixBarcode::DataMatrixBarcode() : d(nullptr) {
 
 }
 
diff --git a/src/lib/qrcodebarcode.cpp b/src/lib/qrcodebarcode.cpp
--- a/src/lib/qrcodebarcode.cpp
+++ b/src/lib/qrcodebarcode.cpp
@@ -39,7 +39,7 @@
 @endcond
 */
 
-QRCodeBarcode::QRCodeBarcode() : AbstractBarcode(), d(0){
+QRCodeBarcode::QRCodeBarcode() : AbstractBarcode(), d(nullptr){
   
 }
 
diff --git a/tests/barcodeexamplewidget.h b/tests/barcodeexamplewidget.h
--- a/tests/barcodeexamplewidget.h
+++ b/tests/barcodeexamplewidget.h
@@ -42,7 +42,7 @@
      * @param barcode The barcode generator for this widget. Takes ownership over the barcode generator
      * @param parent the parent in QWidget hierachy
      */
-    BarcodeExampleWidget(Prison::AbstractBarcode* barcode, QWidget* parent=0);
+    BarcodeExampleWidget(Prison::AbstractBarcode* barcode, QWidget* parent=nullptr);
     virtual ~BarcodeExampleWidget();
     /**
      * sets the data shown to data, and triggers a repaint and resize if needed
diff --git a/tests/prison.cpp b/tests/prison.cpp
--- a/tests/prison.cpp
+++ b/tests/prison.cpp
@@ -128,7 +128,7 @@
     m_93color = new BarcodeExampleWidget(c93colorcode, this);
   }
 
-  m_nullw = new BarcodeExampleWidget(0,this);
+  m_nullw = new BarcodeExampleWidget(nullptr,this);
 
   QSplitter* splitter = new QSplitter(Qt::Vertical);
   splitter->addWidget(m_dmw);