diff --git a/src/ktimecombobox.cpp b/src/ktimecombobox.cpp
--- a/src/ktimecombobox.cpp
+++ b/src/ktimecombobox.cpp
@@ -22,9 +22,72 @@
 #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;
+}
+
+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:
@@ -62,14 +125,16 @@
     QLocale::FormatType m_displayFormat;
     int m_timeListInterval;
     QList<QTime> m_timeList;
+    KTimeValidator *m_validator;
 };
 
 KTimeComboBoxPrivate::KTimeComboBoxPrivate(KTimeComboBox *q)
-    : q(q),
-      m_time(QTime(0, 0, 0)),
-      m_warningShown(false),
-      m_displayFormat(QLocale::ShortFormat),
-      m_timeListInterval(15)
+    : q(q)
+    , m_time(QTime(0, 0, 0))
+    , m_warningShown(false)
+    , m_displayFormat(QLocale::ShortFormat)
+    , m_timeListInterval(15)
+    , m_validator(Q_NULLPTR)
 {
     m_options = KTimeComboBox::EditTime | KTimeComboBox::SelectTime;
     m_minTime = defaultMinTime();
@@ -78,6 +143,9 @@
 
 KTimeComboBoxPrivate::~KTimeComboBoxPrivate()
 {
+    if (m_validator) {
+        delete m_validator;
+    }
 }
 
 QTime KTimeComboBoxPrivate::defaultMinTime()
@@ -154,6 +222,14 @@
     const QLocale locale = q->locale();
     q->lineEdit()->setInputMask(timeFormatToInputMask(locale.timeFormat(m_displayFormat)));
     m_nullString = timeFormatToInputMask(locale.timeFormat(m_displayFormat), true);
+    // Set the validator for the current format
+    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);
@@ -320,10 +396,7 @@
 
 bool KTimeComboBox::isValid() const
 {
-    d->parseTime();
-    return d->m_time.isValid() &&
-           d->m_time >= d->m_minTime &&
-           d->m_time <= d->m_maxTime;
+    return lineEdit()->hasAcceptableInput();
 }
 
 bool KTimeComboBox::isNull() const
@@ -532,3 +605,4 @@
 }
 
 #include "moc_ktimecombobox.cpp"
+#include "ktimecombobox.moc"