diff --git a/qt/main_window.cpp b/qt/main_window.cpp
index d7c3b4a..3883b6b 100644
--- a/qt/main_window.cpp
+++ b/qt/main_window.cpp
@@ -328,8 +328,8 @@ void MainWindow::prefsUpdated()
 
     // Refresh the timer values
     QSettings qs;
-    int timerTotal = qs.value(PrefsDialog::kINTF_TIMER_TOTAL_DURATION).toInt();
-    int timerAlert = qs.value(PrefsDialog::kINTF_TIMER_ALERT_DURATION).toInt();
+    int timerTotal = qs.value(PrefsDialog::kINTF_TIMER_TOTAL_DURATION, 180).toInt();
+    int timerAlert = qs.value(PrefsDialog::kINTF_TIMER_ALERT_DURATION, 30).toInt();
     m_timerModel->setTotalDuration(timerTotal);
     m_timerModel->setAlertDuration(timerAlert);
 
diff --git a/qt/timer_widget.cpp b/qt/timer_widget.cpp
index b064e01..10f93ed 100644
--- a/qt/timer_widget.cpp
+++ b/qt/timer_widget.cpp
@@ -22,6 +22,7 @@
 #include <QtGui/QMouseEvent>
 
 #include "timer_widget.h"
+#include "debug.h"
 
 
 INIT_LOGGER(qt, TimerModel);
@@ -101,11 +102,10 @@ bool TimerModel::isActiveTimer() const
 
 void TimerModel::setTotalDuration(int iSeconds)
 {
+    ASSERT(iSeconds > 0, "Invalid total duration");
     if (iSeconds == m_totalDuration)
         return;
     m_totalDuration = iSeconds;
-    if (m_totalDuration < 0)
-        m_totalDuration = 0;
     emit newTotalDuration(m_totalDuration);
     resetTimer();
 }
@@ -113,6 +113,7 @@ void TimerModel::setTotalDuration(int iSeconds)
 
 void TimerModel::setAlertDuration(int iSeconds)
 {
+    // The duration can be negative (to deactivate the alert)
     if (iSeconds == m_alertDuration)
         return;
     m_alertDuration = iSeconds;
diff --git a/qt/ui/prefs_dialog.ui b/qt/ui/prefs_dialog.ui
index 603ae2e..6d41734 100644
--- a/qt/ui/prefs_dialog.ui
+++ b/qt/ui/prefs_dialog.ui
@@ -48,6 +48,9 @@
             </item>
             <item row="1" column="1">
              <widget class="QSpinBox" name="spinBoxTimerTotal">
+              <property name="minimum">
+               <number>1</number>
+              </property>
               <property name="maximum">
                <number>999</number>
               </property>