diff --git a/Aircraft/Instruments-3d/FG1000/Nasal/ConfigStore.nas b/Aircraft/Instruments-3d/FG1000/Nasal/ConfigStore.nas
index 654591b6c..12737563c 100644
--- a/Aircraft/Instruments-3d/FG1000/Nasal/ConfigStore.nas
+++ b/Aircraft/Instruments-3d/FG1000/Nasal/ConfigStore.nas
@@ -117,6 +117,8 @@ var ConfigStore = {
     "Vr-visible" : 1,
     "Vglide-visible" : 1,
     "Vne-visible": 1,
+
+    "TransponderVFRCode": 1200, # Factory set Transponder code
   },
 
   new : func()
diff --git a/Aircraft/Instruments-3d/FG1000/Nasal/MFDPages/PFDInstruments/PFDInstruments.nas b/Aircraft/Instruments-3d/FG1000/Nasal/MFDPages/PFDInstruments/PFDInstruments.nas
index cb628fb7e..70c2d1ad6 100644
--- a/Aircraft/Instruments-3d/FG1000/Nasal/MFDPages/PFDInstruments/PFDInstruments.nas
+++ b/Aircraft/Instruments-3d/FG1000/Nasal/MFDPages/PFDInstruments/PFDInstruments.nas
@@ -918,9 +918,10 @@ var PFDInstruments =
 
   # Update the Transponder display
   updateTransponder : func(mode, code, ident, edit=0) {
-    # Data validation on the mode
+    # Data validation on the mode and code itself
     if (mode < 0) mode = 0;
     if (mode > 5) mode = 5;
+    if ((code == nil) or (! isnum(code))) code = 0;
 
     # Ensure the code is a 4 digit string representation of a number.
     # Normally this means padding with 0's at the left e.g.  42 becomes 0042.