diff --git a/src/blackgui/selcalcodeselector.cpp b/src/blackgui/selcalcodeselector.cpp
index b90f87219..ccf5ed220 100644
--- a/src/blackgui/selcalcodeselector.cpp
+++ b/src/blackgui/selcalcodeselector.cpp
@@ -10,7 +10,9 @@
 #include "selcalcodeselector.h"
 #include "ui_selcalcodeselector.h"
 #include "blackmisc/avselcal.h"
+#include "blackmisc/icons.h"
 
+using namespace BlackMisc;
 using namespace BlackMisc::Aviation;
 
 namespace BlackGui
@@ -20,12 +22,14 @@ namespace BlackGui
     {
         this->ui->setupUi(this);
         this->resetSelcalCodes(true);
+        this->setValidityHint();
 
         bool c;
-        c = connect(this->ui->cb_SelcalPairs1, SIGNAL(currentIndexChanged(int)), this, SIGNAL(valueChanged()));
+        c = connect(this->ui->cb_SelcalPairs1, SIGNAL(currentIndexChanged(int)), this, SLOT(ps_selcalIndexChanged()));
         Q_ASSERT(c);
-        c = connect(this->ui->cb_SelcalPairs2, SIGNAL(currentIndexChanged(int)), this, SIGNAL(valueChanged()));
+        c = connect(this->ui->cb_SelcalPairs2, SIGNAL(currentIndexChanged(int)), this, SLOT(ps_selcalIndexChanged()));
         Q_ASSERT(c);
+        Q_UNUSED(c);
     }
 
     CSelcalCodeSelector::~CSelcalCodeSelector()
@@ -90,4 +94,24 @@ namespace BlackGui
         this->ui->cb_SelcalPairs1->setCurrentIndex(0);
         this->ui->cb_SelcalPairs2->setCurrentIndex(0);
     }
-}
+
+    void CSelcalCodeSelector::ps_selcalIndexChanged()
+    {
+        this->setValidityHint();
+        emit valueChanged();
+    }
+
+    void CSelcalCodeSelector::setValidityHint()
+    {
+        if (this->hasValidCode())
+        {
+            this->ui->lbl_ValidCodeIcon->setPixmap(CIcons::tick16());
+            this->ui->lbl_ValidCodeIcon->setToolTip("valid SELCAL");
+        }
+        else
+        {
+            this->ui->lbl_ValidCodeIcon->setPixmap(CIcons::cross16());
+            this->ui->lbl_ValidCodeIcon->setToolTip("invalid SELCAL");
+        }
+    }
+}  // namespace
diff --git a/src/blackgui/selcalcodeselector.h b/src/blackgui/selcalcodeselector.h
index 4dcecd25e..78d29f3f6 100644
--- a/src/blackgui/selcalcodeselector.h
+++ b/src/blackgui/selcalcodeselector.h
@@ -57,8 +57,15 @@ namespace BlackGui
         //! Value has been changed
         void valueChanged();
 
+    private slots:
+        //! SELCAL changed
+        void ps_selcalIndexChanged();
+
     private:
         QScopedPointer<Ui::CSelcalCodeSelector> ui;
+
+        //! Set valid/invalid icon
+        void setValidityHint();
     };
 }
 
diff --git a/src/blackgui/selcalcodeselector.ui b/src/blackgui/selcalcodeselector.ui
index 281a5afc5..372f3fc53 100644
--- a/src/blackgui/selcalcodeselector.ui
+++ b/src/blackgui/selcalcodeselector.ui
@@ -41,8 +41,26 @@
    <item>
     <widget class="QComboBox" name="cb_SelcalPairs2"/>
    </item>
+   <item>
+    <widget class="QLabel" name="lbl_ValidCodeIcon">
+     <property name="sizePolicy">
+      <sizepolicy hsizetype="Maximum" vsizetype="Maximum">
+       <horstretch>0</horstretch>
+       <verstretch>0</verstretch>
+      </sizepolicy>
+     </property>
+     <property name="text">
+      <string/>
+     </property>
+     <property name="pixmap">
+      <pixmap resource="../blackmisc/blackmisc.qrc">:/diagona/icons/diagona/icons/tick-button.png</pixmap>
+     </property>
+    </widget>
+   </item>
   </layout>
  </widget>
- <resources/>
+ <resources>
+  <include location="../blackmisc/blackmisc.qrc"/>
+ </resources>
  <connections/>
 </ui>