diff --git a/autotests/krandomtest.cpp b/autotests/krandomtest.cpp
--- a/autotests/krandomtest.cpp
+++ b/autotests/krandomtest.cpp
@@ -26,7 +26,7 @@
 
 #include <QObject>
 #include <QString>
-#include <QRegExp>
+#include <QRegularExpression>
 #include <QVarLengthArray>
 #include <QTextStream>
 #include <QProcess>
@@ -108,11 +108,12 @@
 void KRandomTest::test_randomString()
 {
     const int desiredLength = 12;
-    const QRegExp outputFormat(QStringLiteral("[A-Za-z0-9]+"));
-    QString testString = KRandom::randomString(desiredLength);
+    const QString testString = KRandom::randomString(desiredLength);
+    const QRegularExpression outputFormat(QRegularExpression::anchoredPattern(QStringLiteral("[A-Za-z0-9]+")));
+    const QRegularExpressionMatch match = outputFormat.match(testString);
 
     QCOMPARE(testString.length(), desiredLength);
-    QVERIFY(outputFormat.exactMatch(testString));
+    QVERIFY(match.hasMatch());
 }
 
 void KRandomTest::test_KRS()
diff --git a/src/lib/io/kfileutils.cpp b/src/lib/io/kfileutils.cpp
--- a/src/lib/io/kfileutils.cpp
+++ b/src/lib/io/kfileutils.cpp
@@ -20,6 +20,7 @@
 
 #include <QMimeDatabase>
 #include <QFileInfo>
+#include <QRegularExpression>
 
 QString KFileUtils::suggestName(const QUrl &baseURL, const QString &oldName)
 {
@@ -45,13 +46,14 @@
         basename = oldName.left(oldName.length() - nameSuffix.length());
     }
 
-    // check if (number) exists from the end of the oldName and increment that number
-    QRegExp numSearch(QStringLiteral("\\(\\d+\\)"));
-    int start = numSearch.lastIndexIn(oldName);
-    if (start != -1) {
-        QString numAsStr = numSearch.cap(0);
-        QString number = QString::number(numAsStr.midRef(1, numAsStr.size() - 2).toInt() + 1);
-        basename = basename.leftRef(start) + QLatin1Char('(') + number + QLatin1Char(')');
+    // check if (number) exists at the end of the oldName and increment that number
+    const QRegularExpression re(QStringLiteral("\\((\\d+)\\)"));
+    QRegularExpressionMatch rmatch;
+    oldName.lastIndexOf(re, -1, &rmatch);
+    if (rmatch.hasMatch()) {
+        const int currentNum = rmatch.captured(1).toInt();
+        const QString number = QString::number(currentNum + 1);
+        basename.replace(rmatch.capturedStart(1), rmatch.capturedLength(1), number);
     } else {
         // number does not exist, so just append " (1)" to filename
         basename += QLatin1String(" (1)");
diff --git a/src/lib/text/kmacroexpander_unix.cpp b/src/lib/text/kmacroexpander_unix.cpp
--- a/src/lib/text/kmacroexpander_unix.cpp
+++ b/src/lib/text/kmacroexpander_unix.cpp
@@ -24,7 +24,7 @@
 
 #include <QStringList>
 #include <QStack>
-#include <QRegExp>
+#include <QRegularExpression>
 
 namespace KMacroExpander
 {
@@ -114,10 +114,10 @@
         }
         if (state.dquote) {
             rsts = rst.join(QLatin1Char(' '));
-            rsts.replace(QRegExp(QStringLiteral("([$`\"\\\\])")), QStringLiteral("\\\\1"));
+            rsts.replace(QRegularExpression(QStringLiteral("([$`\"\\\\])")), QStringLiteral("\\\\1"));
         } else if (state.current == dollarquote) {
             rsts = rst.join(QLatin1Char(' '));
-            rsts.replace(QRegExp(QStringLiteral("(['\\\\])")), QStringLiteral("\\\\1"));
+            rsts.replace(QRegularExpression(QStringLiteral("(['\\\\])")), QStringLiteral("\\\\1"));
         } else if (state.current == singlequote) {
             rsts = rst.join(QLatin1Char(' '));
             rsts.replace(QLatin1Char('\''), QLatin1String("'\\''"));
diff --git a/src/lib/text/kstringhandler.cpp b/src/lib/text/kstringhandler.cpp
--- a/src/lib/text/kstringhandler.cpp
+++ b/src/lib/text/kstringhandler.cpp
@@ -24,6 +24,7 @@
 #include <stdlib.h>     // random()
 
 #include <QRegExp>            // for the word ranges
+#include <QRegularExpression>
 #include <QCharRef>
 #include <QStringList>
 #include <QVector>
@@ -166,24 +167,12 @@
 
 QString KStringHandler::tagUrls(const QString &text)
 {
-    /*static*/ QRegExp urlEx(QStringLiteral("(www\\.(?!\\.)|(fish|(f|ht)tp(|s))://)[\\d\\w\\./,:_~\\?=&;#@\\-\\+\\%\\$\\(]+[\\d\\w/\\)]"));
-
     QString richText(text);
-    int urlPos = 0, urlLen;
-    while ((urlPos = urlEx.indexIn(richText, urlPos)) >= 0) {
-        urlLen = urlEx.matchedLength();
-        QString href = richText.mid(urlPos, urlLen);
-        // Qt doesn't support (?<=pattern) so we do it here
-        if ((urlPos > 0) && richText[urlPos - 1].isLetterOrNumber()) {
-            urlPos++;
-            continue;
-        }
-        // Don't use QString::arg since %01, %20, etc could be in the string
-        QString anchor = QLatin1String("<a href=\"") + href + QLatin1String("\">") + href + QLatin1String("</a>");
-        richText.replace(urlPos, urlLen, anchor);
-
-        urlPos += anchor.length();
-    }
+    const QRegularExpression urlEx(QStringLiteral("(www\\.(?!\\.)|(fish|ftp|http|https)://[\\d\\w\\./,:_~\\?=&;#@\\-\\+\\%\\$\\(\\)]+)"));
+    // the reference \1 is going to be replaced by the matched url
+    const QLatin1String regexBackRef(QLatin1String("\\1"));
+    const QString anchor = QLatin1String("<a href=\"") + regexBackRef + QLatin1String("\">") + regexBackRef + QLatin1String("</a>");
+    richText.replace(urlEx, anchor);
     return richText;
 }
 
diff --git a/src/lib/util/klistopenfilesjob_unix.cpp b/src/lib/util/klistopenfilesjob_unix.cpp
--- a/src/lib/util/klistopenfilesjob_unix.cpp
+++ b/src/lib/util/klistopenfilesjob_unix.cpp
@@ -23,6 +23,7 @@
 #include "klistopenfilesjob.h"
 #include <QDir>
 #include <QProcess>
+#include <QRegularExpression>
 
 class KListOpenFilesJobPrivate
 {
@@ -65,7 +66,7 @@
             return;
         }
         const QString out(QString::fromLocal8Bit(lsofProcess.readAll()));
-        QStringList pidList = out.split(QRegExp(QStringLiteral("\\s+")), QString::SkipEmptyParts);
+        QStringList pidList = out.split(QRegularExpression(QStringLiteral("\\s+")), QString::SkipEmptyParts);
         pidList.removeDuplicates();
         for (const auto& pidStr : qAsConst(pidList)) {
             qint64 pid = pidStr.toLongLong();
diff --git a/src/lib/util/kshell_win.cpp b/src/lib/util/kshell_win.cpp
--- a/src/lib/util/kshell_win.cpp
+++ b/src/lib/util/kshell_win.cpp
@@ -23,6 +23,7 @@
 #include "kshell.h"
 #include "kshell_p.h"
 
+#include <QRegularExpression>
 #include <QString>
 #include <QStringList>
 #include <QDir>
@@ -269,7 +270,7 @@
     // Escape quotes. Preceding backslashes are doubled.
     // Note that the remaining string is not quoted.
     QString ret(arg);
-    ret.replace(QRegExp(QLatin1String("(\\\\*)\"")), QLatin1String("\\1\\1\\^\""));
+    ret.replace(QRegularExpression(QStringLiteral("(\\\\*)\"")), QStringLiteral("\\1\\1\\^\""));
     ret.replace(QLatin1Char('%'), PERCENT_ESCAPE);
     return ret;
 }