diff --git a/plugins/vnc/vinagre-vnc-connection.h b/plugins/vnc/vinagre-vnc-connection.h
index 4788ae2..f37642c 100644
--- a/plugins/vnc/vinagre-vnc-connection.h
+++ b/plugins/vnc/vinagre-vnc-connection.h
@@ -26,7 +26,7 @@
 
 G_BEGIN_DECLS
 
-gboolean scaling_command_line;
+extern gboolean scaling_command_line;
 
 #define VINAGRE_TYPE_VNC_CONNECTION             (vinagre_vnc_connection_get_type ())
 #define VINAGRE_VNC_CONNECTION(obj)             (G_TYPE_CHECK_INSTANCE_CAST ((obj), VINAGRE_TYPE_VNC_CONNECTION, VinagreVncConnection))
diff --git a/plugins/vnc/vinagre-vnc-plugin.c b/plugins/vnc/vinagre-vnc-plugin.c
index a5884da..438aa99 100644
--- a/plugins/vnc/vinagre-vnc-plugin.c
+++ b/plugins/vnc/vinagre-vnc-plugin.c
@@ -35,6 +35,8 @@
 #include "vinagre-vnc-connection.h"
 #include "vinagre-vnc-tab.h"
 
+gboolean scaling_command_line;
+
 void vnc_register_types (void);
 
 static void vinagre_vnc_protocol_iface_init (VinagreProtocolInterface *iface);
