diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
index b01c044..a8b4c0b 100644
--- a/include/media/v4l2-ioctl.h
+++ b/include/media/v4l2-ioctl.h
@@ -267,6 +267,7 @@
 
 /*  Video standard functions  */
 extern const char *v4l2_norm_to_name(v4l2_std_id id);
+extern void v4l2_video_std_frame_period(int id, struct v4l2_fract *frameperiod);
 extern int v4l2_video_std_construct(struct v4l2_standard *vs,
 				    int id, const char *name);
 /* Prints the ioctl in a human-readable format */