diff --git a/src/Aircraft/aircraft.cxx b/src/Aircraft/aircraft.cxx
index bfe7c81ba..e88fb83e4 100644
--- a/src/Aircraft/aircraft.cxx
+++ b/src/Aircraft/aircraft.cxx
@@ -140,7 +140,7 @@ void fgReadAircraft(void) {
    globals->get_commands()->addCommand("load-aircraft", fgLoadAircraft);
 }
 
-bool
+static bool
 fgLoadAircraft (const SGPropertyNode * arg)
 {
     static const SGPropertyNode *master_freeze
diff --git a/src/Aircraft/aircraft.hxx b/src/Aircraft/aircraft.hxx
index 65450ffb1..94fd6db3c 100644
--- a/src/Aircraft/aircraft.hxx
+++ b/src/Aircraft/aircraft.hxx
@@ -59,7 +59,7 @@ void fgAircraftOutputCurrent(fgAIRCRAFT *a);
 
 // Read the list of available aircraft into to property tree
 void fgReadAircraft(void);
-bool fgLoadAircraft (const SGPropertyNode * arg);
+static bool fgLoadAircraft (const SGPropertyNode * arg);
 
 #endif // _AIRCRAFT_HXX