diff --git a/src/ktimecombobox.cpp b/src/ktimecombobox.cpp
--- a/src/ktimecombobox.cpp
+++ b/src/ktimecombobox.cpp
@@ -22,9 +22,76 @@
 #include <QtCore/QTime>
 #include <QKeyEvent>
 #include <QLineEdit>
+#include <QValidator>
 
 #include "kmessagebox.h"
 
+class KTimeValidator : public QValidator
+{
+    Q_OBJECT
+public:
+    KTimeValidator(QString timeFormat, QObject *parent = Q_NULLPTR);
+    KTimeValidator(QString timeFormat, QTime min, QTime max, QObject *parent = Q_NULLPTR);
+    ~KTimeValidator();
+    virtual State validate(QString &input, int &pos) const Q_DECL_OVERRIDE;
+    void setMin(QTime min);
+    void setMax(QTime max);
+
+private:
+    QString m_timeFormat;
+    QTime m_min, m_max;
+};
+
+KTimeValidator::KTimeValidator(QString timeFormat, QObject *parent)
+    :
+    QValidator(parent),
+    m_timeFormat(timeFormat)
+{
+}
+
+KTimeValidator::KTimeValidator(QString timeFormat, QTime min, QTime max, QObject *parent)
+    :
+    QValidator(parent),
+    m_timeFormat(timeFormat),
+    m_min(min),
+    m_max(max)
+{
+}
+
+KTimeValidator::~KTimeValidator()
+{
+}
+
+
+void KTimeValidator::setMax(QTime max)
+{
+    m_max = max;
+}
+
+void KTimeValidator::setMin(QTime min)
+{
+    m_min = min;
+}
+
+
+KTimeValidator::QValidator::State KTimeValidator::validate(QString& input, int& pos) const
+{
+    Q_UNUSED(pos);
+    QTime t = QTime::fromString(input, m_timeFormat);
+    if (t.isValid()){
+        if (m_min.isValid() && t < m_min)
+            return State::Invalid;
+        if (m_max.isValid() && t > m_max)
+            return State::Invalid;
+
+        return State::Acceptable;
+    }
+    else{
+        return State::Invalid;
+    }
+}
+
+
 class KTimeComboBoxPrivate
 {
 public:
@@ -35,7 +102,6 @@
     QTime defaultMinTime();
     QTime defaultMaxTime();
 
-    QString timeFormatToInputMask(const QString &format, bool nullMask = false);
     QTime nearestIntervalTime(const QTime &time);
     QString formatTime(const QTime &time);
 
@@ -62,6 +128,7 @@
     QLocale::FormatType m_displayFormat;
     int m_timeListInterval;
     QList<QTime> m_timeList;
+    KTimeValidator *m_validator;
 };
 
 KTimeComboBoxPrivate::KTimeComboBoxPrivate(KTimeComboBox *q)
@@ -69,7 +136,8 @@
       m_time(QTime(0, 0, 0)),
       m_warningShown(false),
       m_displayFormat(QLocale::ShortFormat),
-      m_timeListInterval(15)
+      m_timeListInterval(15),
+      m_validator(Q_NULLPTR)
 {
     m_options = KTimeComboBox::EditTime | KTimeComboBox::SelectTime;
     m_minTime = defaultMinTime();
@@ -78,6 +146,8 @@
 
 KTimeComboBoxPrivate::~KTimeComboBoxPrivate()
 {
+    if (m_validator)
+        delete m_validator;
 }
 
 QTime KTimeComboBoxPrivate::defaultMinTime()
@@ -90,41 +160,6 @@
     return QTime(23, 59, 59, 999);
 }
 
-QString KTimeComboBoxPrivate::timeFormatToInputMask(const QString &format, bool nullMask)
-{
-    const QLocale locale = q->locale();
-
-    //TODO not sure this will always work, does it support DigitSets, am/pm is dodgy?
-    QString mask = formatTime(QTime(12, 34, 56, 789));
-    QString null = mask;
-    mask.replace(locale.toString(12), QLatin1String("09"));
-    null.replace(locale.toString(12), QLatin1String(""));
-    mask.replace(locale.toString(34), QLatin1String("99"));
-    null.replace(locale.toString(34), QLatin1String(""));
-    mask.replace(locale.toString(56), QLatin1String("99"));
-    null.replace(locale.toString(56), QLatin1String(""));
-    mask.replace(locale.toString(789), QLatin1String("900"));
-    null.replace(locale.toString(789), QLatin1String(""));
-    if (format.contains(QLatin1String("ap")) ||
-            format.contains(QLatin1String("AP"))) {
-        QString am = locale.amText();
-        QString pm = locale.pmText();
-        int ampmLen = qMax(am.length(), pm.length());
-        QString ampmMask;
-        for (int i = 0; i < ampmLen; ++i) {
-            ampmMask.append(QLatin1Char('a'));
-        }
-        mask.replace(pm, ampmMask);
-        null.replace(pm, QLatin1String(""));
-    }
-
-    if (nullMask) {
-        return null;
-    } else {
-        return mask;
-    }
-}
-
 QTime KTimeComboBoxPrivate::nearestIntervalTime(const QTime &time)
 {
     int i = 0;
@@ -150,10 +185,15 @@
     q->blockSignals(true);
     q->clear();
 
-    // Set the input mask from the current format
+    // Set the validator for the current format
     const QLocale locale = q->locale();
-    q->lineEdit()->setInputMask(timeFormatToInputMask(locale.timeFormat(m_displayFormat)));
-    m_nullString = timeFormatToInputMask(locale.timeFormat(m_displayFormat), true);
+    if (m_validator){
+        q->lineEdit()->setValidator(Q_NULLPTR);
+        delete m_validator;
+    }
+    m_validator = new KTimeValidator(locale.timeFormat(m_displayFormat),
+                                     m_minTime, m_maxTime);
+    q->lineEdit()->setValidator(m_validator);
 
     // If EditTime then set the line edit
     q->lineEdit()->setReadOnly((m_options & KTimeComboBox::EditTime) != KTimeComboBox::EditTime);
@@ -532,3 +572,4 @@
 }
 
 #include "moc_ktimecombobox.cpp"
+#include "ktimecombobox.moc"