diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index f9ca7d19781a5691eb915c8764873ba82b31fcf0..0d6b17057188581665027d9113cfcd668032cf4c 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -57,8 +57,6 @@ void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime)
 	dl_b->dl_runtime = runtime;
 }
 
-extern unsigned long to_ratio(u64 period, u64 runtime);
-
 void init_dl_bw(struct dl_bw *dl_b)
 {
 	raw_spin_lock_init(&dl_b->lock);