diff --git a/sw/simulator/fg.c b/sw/simulator/fg.c
index 19bd9c7a91a..f043a516f02 100644
--- a/sw/simulator/fg.c
+++ b/sw/simulator/fg.c
@@ -24,7 +24,7 @@ value fg_msg_bytecode(value *argv, int argc) {
 
 value fg_msg_native(value s, value lat, value lon, value z, value phi, value theta, value psi) {
 
-  struct FGNetGUI msg;
+  struct FGNetGUI msg = {0};
   msg.version = FG_NET_GUI_VERSION;
 
   msg.longitude = Double_val(lon);