diff --git a/sys/powerpc/aim/aim_machdep.c b/sys/powerpc/aim/aim_machdep.c
index 7a42bc6b960e..3140de8d8977 100644
--- a/sys/powerpc/aim/aim_machdep.c
+++ b/sys/powerpc/aim/aim_machdep.c
@@ -747,7 +747,7 @@ flush_disable_caches(void)
 
 #ifndef __powerpc64__
 void
-mpc745x_sleep()
+mpc745x_sleep(void)
 {
 	static u_quad_t timebase = 0;
 	static register_t sprgs[4];