diff --git a/index.html b/index.html
index 5ae4d5e..4561615 100644
--- a/index.html
+++ b/index.html
@@ -80,14 +80,18 @@
         <div class="inner">
         <h2>Select Serial Port</h2>
         <p>Available Ports:
-        <select name="ports" class="select" id="portsSelect" size="10" width="20"></select>
+        <select name="ports" class="select" id="portsSelect" size="10" width="20" onClick="checkForValidPort()"></select>
         <ul class="actions">
                 <!--  <li><input type='button' value="Install Serial Drivers" onclick="installDrivers();" /></li> -->
                 <li><input type='button' value="Refresh" onclick="refreshSerialPorts();" /></li>
                 <li><input type='button' value="Upload" id="btnInstall" /></li>
         </ul>
+        <div class="features major" id="port_warning" style="display: none;">
+            <div id="port_warningText" style="padding-left: 0.9em; padding-right: 0.9em; overflow-y: scroll; height: 10vh;"></div>
+        </div>
         </p>
         </div>
+        
        
         <div id="serialDetectError"></div>
 </section>
diff --git a/renderer.js b/renderer.js
index c2795eb..35b968b 100644
--- a/renderer.js
+++ b/renderer.js
@@ -152,6 +152,33 @@ function refreshSerialPorts()
   })
 }
 
+//Checks whether the port currently selected is a known invalid one or not
+function checkForValidPort()
+{
+  var validPort = true;
+  var errorText = ""
+  var option = document.getElementById('portsSelect').options[document.getElementById('portsSelect').selectedIndex];
+
+  if(option.getAttribute('board') == "STM32F407_serial")
+  {
+    validPort = false;
+    errorText = "Serial mode is not supported on STM32F407 boards. Please place the board into DFU mode instead.";
+  }
+
+  if(validPort)
+  {
+    document.getElementById('port_warning').style.display = "none";
+    document.getElementById('port_warningText').innerHTML = "";
+    document.getElementById('btnInstall').disabled = false;
+  }
+  else
+  {
+    document.getElementById('port_warning').style.display = "block";
+    document.getElementById('port_warningText').innerHTML = errorText;
+    document.getElementById('btnInstall').disabled = true;
+  }
+}
+
 function refreshDetails()
 {
     var selectElement = document.getElementById('versionsSelect');