diff --git a/src/backends/R/rkeywords.cpp b/src/backends/R/rkeywords.cpp
--- a/src/backends/R/rkeywords.cpp
+++ b/src/backends/R/rkeywords.cpp
@@ -38,7 +38,7 @@
 
     if(inst == nullptr){
         inst = new RKeywords();
-        qSort(inst->m_keywords);
+        std::sort(inst->m_keywords.begin(), inst->m_keywords.end());
     }
 
     return inst;
diff --git a/src/backends/maxima/maximacompletionobject.cpp b/src/backends/maxima/maximacompletionobject.cpp
--- a/src/backends/maxima/maximacompletionobject.cpp
+++ b/src/backends/maxima/maximacompletionobject.cpp
@@ -36,15 +36,15 @@
 {
     QStringList userVariableNames=session()->variableModel()->variableNames();
     QStringList userFunctionNames=session()->variableModel()->functions();
-    if (qBinaryFind(userVariableNames.begin(), userVariableNames.end(), identifier()) != userVariableNames.end())
+    if (std::binary_search(userVariableNames.begin(), userVariableNames.end(), identifier()))
         emit fetchingTypeDone(VariableType);
-    else if (qBinaryFind(userFunctionNames.begin(), userFunctionNames.end(), identifier()) != userFunctionNames.end())
+    else if (std::binary_search(userFunctionNames.begin(), userFunctionNames.end(), identifier()))
         emit fetchingTypeDone(FunctionType);
-    else if (qBinaryFind(MaximaKeywords::instance()->functions().begin(),
-            MaximaKeywords::instance()->functions().end(), identifier()) != MaximaKeywords::instance()->functions().end())
+    else if (std::binary_search(MaximaKeywords::instance()->functions().begin(),
+            MaximaKeywords::instance()->functions().end(), identifier()))
         emit fetchingTypeDone(FunctionType);
-    else if (qBinaryFind(MaximaKeywords::instance()->keywords().begin(),
-            MaximaKeywords::instance()->keywords().end(), identifier()) != MaximaKeywords::instance()->keywords().end())
+    else if (std::binary_search(MaximaKeywords::instance()->keywords().begin(),
+            MaximaKeywords::instance()->keywords().end(), identifier()))
         emit fetchingTypeDone(KeywordType);
     else
         emit fetchingTypeDone(VariableType);
diff --git a/src/backends/maxima/maximakeywords.cpp b/src/backends/maxima/maximakeywords.cpp
--- a/src/backends/maxima/maximakeywords.cpp
+++ b/src/backends/maxima/maximakeywords.cpp
@@ -56,9 +56,9 @@
     m_functions << QLatin1String("celine");
 
     // We use qBinarySearch with this lists
-    qSort(m_keywords);
-    qSort(m_functions);
-    qSort(m_variables);
+    std::sort(m_keywords.begin(), m_keywords.end());
+    std::sort(m_functions.begin(), m_functions.end());
+    std::sort(m_variables.begin(), m_variables.end());
 }
 
 const QStringList& MaximaKeywords::variables() const
diff --git a/src/backends/octave/octavekeywords.cpp b/src/backends/octave/octavekeywords.cpp
--- a/src/backends/octave/octavekeywords.cpp
+++ b/src/backends/octave/octavekeywords.cpp
@@ -71,8 +71,8 @@
 
     if(inst == nullptr){
         inst = new OctaveKeywords();
-        qSort(inst->m_functions);
-        qSort(inst->m_keywords);
+        std::sort(inst->m_functions.begin(), inst->m_functions.end());
+        std::sort(inst->m_keywords.begin(), inst->m_keywords.end());
     }
 
     return inst;
diff --git a/src/backends/python/pythoncompletionobject.cpp b/src/backends/python/pythoncompletionobject.cpp
--- a/src/backends/python/pythoncompletionobject.cpp
+++ b/src/backends/python/pythoncompletionobject.cpp
@@ -77,13 +77,11 @@
 {
     if (session()->status() != Cantor::Session::Done)
     {
-        if (qBinaryFind(PythonKeywords::instance()->functions().begin(),
-                PythonKeywords::instance()->functions().end(), identifier())
-        != PythonKeywords::instance()->functions().end())
+        if (std::binary_search(PythonKeywords::instance()->functions().begin(),
+                PythonKeywords::instance()->functions().end(), identifier()))
         emit fetchingTypeDone(FunctionType);
-        else if (qBinaryFind(PythonKeywords::instance()->keywords().begin(),
-                PythonKeywords::instance()->keywords().end(), identifier())
-        != PythonKeywords::instance()->keywords().end())
+        else if (std::binary_search(PythonKeywords::instance()->keywords().begin(),
+                PythonKeywords::instance()->keywords().end(), identifier()))
         emit fetchingTypeDone(KeywordType);
         else
         emit fetchingTypeDone(VariableType);
diff --git a/src/backends/python/pythonkeywords.cpp b/src/backends/python/pythonkeywords.cpp
--- a/src/backends/python/pythonkeywords.cpp
+++ b/src/backends/python/pythonkeywords.cpp
@@ -60,9 +60,9 @@
     m_variables << definition.keywordList(QLatin1String("specialvars"));
 
     // We use qBinarySearch in PythonCompletetionObject for type fetching
-    qSort(m_keywords);
-    qSort(m_functions);
-    qSort(m_variables);
+    std::sort(m_keywords.begin(), m_keywords.end());
+    std::sort(m_functions.begin(), m_functions.end());
+    std::sort(m_variables.begin(), m_variables.end());
 }
 
 void PythonKeywords::loadFromModule(const QString& module, const QStringList& keywords)
diff --git a/src/backends/scilab/scilabcompletionobject.cpp b/src/backends/scilab/scilabcompletionobject.cpp
--- a/src/backends/scilab/scilabcompletionobject.cpp
+++ b/src/backends/scilab/scilabcompletionobject.cpp
@@ -51,11 +51,11 @@
     // Scilab's typeof function could be used here, but as long as these lists
     // are used just looking up the name is easier.
 
-    if (qBinaryFind(ScilabKeywords::instance()->functions().begin(), ScilabKeywords::instance()->functions().end(),
-            identifier()) != ScilabKeywords::instance()->functions().end())
+    if (std::binary_search(ScilabKeywords::instance()->functions().begin(), ScilabKeywords::instance()->functions().end(),
+            identifier()))
         emit fetchingTypeDone(FunctionType);
-    else if (qBinaryFind(ScilabKeywords::instance()->keywords().begin(),ScilabKeywords::instance()->keywords().end(),
-            identifier()) != ScilabKeywords::instance()->keywords().end())
+    else if (std::binary_search(ScilabKeywords::instance()->keywords().begin(),ScilabKeywords::instance()->keywords().end(),
+            identifier()))
         emit fetchingTypeDone(KeywordType);
     else
         emit fetchingTypeDone(VariableType);
diff --git a/src/backends/scilab/scilabkeywords.cpp b/src/backends/scilab/scilabkeywords.cpp
--- a/src/backends/scilab/scilabkeywords.cpp
+++ b/src/backends/scilab/scilabkeywords.cpp
@@ -55,9 +55,9 @@
 
     if(inst == nullptr){
         inst = new ScilabKeywords();
-        qSort(inst->m_variables);
-        qSort(inst->m_functions);
-        qSort(inst->m_keywords);
+        std::sort(inst->m_variables.begin(), inst->m_variables.end());
+        std::sort(inst->m_functions.begin(), inst->m_functions.end());
+        std::sort(inst->m_keywords.begin(), inst->m_keywords.end());
     }
 
     return inst;
diff --git a/src/commandentry.cpp b/src/commandentry.cpp
--- a/src/commandentry.cpp
+++ b/src/commandentry.cpp
@@ -36,6 +36,7 @@
 #include <QDebug>
 #include <QDesktopWidget>
 #include <QFontDialog>
+#include <QScreen>
 #include <QTimer>
 #include <QToolTip>
 #include <QPropertyAnimation>
@@ -1156,8 +1157,8 @@
 {
     const QPointF cursorPos = m_commandItem->cursorPosition();
     const QPoint globalPos = toGlobalPosition(cursorPos);
-    const QDesktopWidget* desktop = QApplication::desktop();
-    const QRect screenRect = desktop->screenGeometry(globalPos);
+    const QScreen* desktop = QGuiApplication::primaryScreen();
+    const QRect screenRect = desktop->geometry();
     if (globalPos.y() + m_completionBox->height() < screenRect.bottom()) {
         return (globalPos);
     } else {
diff --git a/src/lib/backend.cpp b/src/lib/backend.cpp
--- a/src/lib/backend.cpp
+++ b/src/lib/backend.cpp
@@ -28,6 +28,7 @@
 #include <KPluginFactory>
 #include <KPluginMetaData>
 #include <QDir>
+#include <QRegularExpression>
 #include <QUrl>
 
 #include "extension.h"
@@ -188,7 +189,7 @@
 
 QStringList Backend::extensions() const
 {
-    QList<Extension*> extensions=findChildren<Extension*>(QRegExp(QLatin1String(".*Extension")));
+    QList<Extension*> extensions=findChildren<Extension*>(QRegularExpression(QLatin1String(".*Extension")));
     QStringList names;
     foreach(Extension* e, extensions)
         names<<e->objectName();
diff --git a/src/worksheet.cpp b/src/worksheet.cpp
--- a/src/worksheet.cpp
+++ b/src/worksheet.cpp
@@ -756,14 +756,14 @@
         return;
 
     QTextDocument *oldDocument = m_highlighter->document();
-    QList<QList<QTextLayout::FormatRange> > formats;
+    QList<QVector<QTextLayout::FormatRange> > formats;
 
     if (oldDocument)
     {
         for (QTextBlock b = oldDocument->firstBlock();
              b.isValid(); b = b.next())
         {
-            formats.append(b.layout()->additionalFormats());
+            formats.append(b.layout()->formats());
         }
     }
 
@@ -783,7 +783,7 @@
         for (QTextBlock b = oldDocument->firstBlock();
              b.isValid(); b = b.next())
         {
-            b.layout()->setAdditionalFormats(formats.first());
+            b.layout()->setFormats(formats.first());
             formats.pop_front();
         }
         cursor.endEditBlock();
@@ -821,7 +821,7 @@
             for (QTextBlock b = item->document()->firstBlock();
                  b.isValid(); b = b.next())
             {
-                b.layout()->clearAdditionalFormats();
+                b.layout()->clearFormats();
             }
             cursor.endEditBlock();
         }