diff --git a/src/frontend/stmclient.h b/src/frontend/stmclient.h
index 0b79991..51150c6 100644
--- a/src/frontend/stmclient.h
+++ b/src/frontend/stmclient.h
@@ -68,7 +68,7 @@ private:
 
   void output_new_frame( void );
 
-  bool still_connecting( void )
+  bool still_connecting( void ) const
   {
     /* Initially, network == NULL */
     return network && ( network->get_remote_state_num() == 0 );