--- a/prince/include/common.h
+++ b/prince/include/common.h
@@ -35,12 +35,12 @@ typedef struct routing_plugin_ {
 
 } routing_plugin;
 
-routing_plugin *(*new_plugin_p)(char *host, int port, int json_type,
+static routing_plugin *(*new_plugin_p)(char *host, int port, int json_type,
 				int timer_port);
 
-int (*get_initial_timers_p)(routing_plugin *o, struct timers *t);
-int (*get_topology_p)(routing_plugin *o);
-int (*push_timers_p)(routing_plugin *o, struct timers t);
-void (*delete_plugin_p)(routing_plugin *o);
+static int (*get_initial_timers_p)(routing_plugin *o, struct timers *t);
+static int (*get_topology_p)(routing_plugin *o);
+static int (*push_timers_p)(routing_plugin *o, struct timers t);
+static void (*delete_plugin_p)(routing_plugin *o);
 
 #endif /* SRC_COMMON_H_ */