diff --git a/src/Main/globals.cxx b/src/Main/globals.cxx
index 4008ba180..e6a310535 100644
--- a/src/Main/globals.cxx
+++ b/src/Main/globals.cxx
@@ -145,7 +145,7 @@ FGGlobals::add_event (const char * name,
 
 void
 FGGlobals::add_event (const char * name,
-                      const SGSubsystem * subsystem,
+                      SGSubsystem * subsystem,
                       int repeat_value,
                       int initial_value)
 {
diff --git a/src/Main/globals.hxx b/src/Main/globals.hxx
index 3104989b2..67dbf19fd 100644
--- a/src/Main/globals.hxx
+++ b/src/Main/globals.hxx
@@ -220,7 +220,7 @@ public:
                             int initial_value = -1 );
 
     virtual void add_event (const char * name,
-                            const SGSubsystem * subsystem,
+                            SGSubsystem * subsystem,
                             int repeat_value,
                             int initial_value = -1 );
 
@@ -236,7 +236,7 @@ public:
 
     template< typename Fun >
     inline void add_event( const char * name,
-                           const SGSubsystem * subsystem,
+                           SGSubsystem * subsystem,
                            const Fun& func,
                            SGEvent::interval_type repeat_value,
                            SGEvent::interval_type initial_value = -1 )