diff --git a/src/gui/peptide_detail_view/peptide_detail_view.ui b/src/gui/peptide_detail_view/peptide_detail_view.ui
index f17ecdd4ebfae7509a67ec94406275fac139e9a0..e86a541a1da269e3390a76eace7d3da712afe16e 100644
--- a/src/gui/peptide_detail_view/peptide_detail_view.ui
+++ b/src/gui/peptide_detail_view/peptide_detail_view.ui
@@ -144,7 +144,7 @@
              </widget>
             </item>
            </layout>
-	   </widget>
+	 </widget>
           </item>
           <item>
            <layout class="QHBoxLayout" name="horizontalLayout_2">
@@ -396,10 +396,27 @@
     </hint>
    </hints>
   </connection>
+  <connection>
+   <sender>precision_unit_combobox</sender>
+   <signal>currentIndexChanged(QString)</signal>
+   <receiver>PeptideDetailView</receiver>
+   <slot>doMsmsPrecisionUnitChanged(QString)</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>680</x>
+     <y>355</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>873</x>
+     <y>278</y>
+    </hint>
+   </hints>
+  </connection>
  </connections>
  <slots>
   <slot>chooseDefaultMzDataDir()</slot>
   <slot>openInPeptideViewer()</slot>
   <slot>doMsmsPrecisionValueChanged(double)</slot>
+  <slot>doMsmsPrecisionUnitChanged(QString)</slot>
  </slots>
 </ui>
diff --git a/src/gui/peptide_detail_view/peptidewindow.cpp b/src/gui/peptide_detail_view/peptidewindow.cpp
index 776aa15769d0b4661db6fdde975ca1ef8f8731e8..27a208e53fa70882d92c89e460b3cdcb70e21097 100644
--- a/src/gui/peptide_detail_view/peptidewindow.cpp
+++ b/src/gui/peptide_detail_view/peptidewindow.cpp
@@ -227,6 +227,24 @@ void PeptideWindow::setPeptideMatch(PeptideMatch * p_peptide_match) {
     qDebug() << "PeptideWindow::setPeptideMatch end";
 }
 
+void PeptideWindow::doMsmsPrecisionUnitChanged(QString unit) {
+
+  qDebug() << "PeptideWindow::doMsmsPrecisionUnitChanged begin " << unit;
+    QSettings settings;
+    pappso::mz precision = ui->precision_spinbox->value();
+
+
+    if (unit == "dalton") {
+        _p_precision = Precision::getDaltonInstance(precision);
+    } else {
+        _p_precision = Precision::getPpmInstance(precision);
+    }
+    ui->spectrumWidget->setPrecision(_p_precision);
+
+    settings.setValue("peptideview/precision_unit", unit);
+    
+  qDebug() << "PeptideWindow::doMsmsPrecisionUnitChanged end " << unit;
+}
 
 void PeptideWindow::doMsmsPrecisionValueChanged(double precision_value) {
 
@@ -242,6 +260,5 @@ void PeptideWindow::doMsmsPrecisionValueChanged(double precision_value) {
     }
     ui->spectrumWidget->setPrecision(_p_precision);
 
-    settings.setValue("peptideview/precision_unit", unit);
     settings.setValue("peptideview/precision_value", precision);
 }
diff --git a/src/gui/peptide_detail_view/peptidewindow.h b/src/gui/peptide_detail_view/peptidewindow.h
index 7811316cb35d20d1a3740192971ce9a48cbd52fc..33628df4ec6c847292149dc2527262095446ff0c 100644
--- a/src/gui/peptide_detail_view/peptidewindow.h
+++ b/src/gui/peptide_detail_view/peptidewindow.h
@@ -77,6 +77,7 @@ signals:
 protected slots:
     void doSpectrumSpReady(pappso::SpectrumSp spectrum_sp, QString error);
     void doMsmsPrecisionValueChanged(double precision_value);
+    void doMsmsPrecisionUnitChanged(QString unit);
     void chooseDefaultMzDataDir();
     void openInPeptideViewer();
 protected :