diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 53cb49a..9595c2c 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -855,6 +855,7 @@
 extern int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid);
 extern void drm_mode_probed_add(struct drm_connector *connector, struct drm_display_mode *mode);
 extern void drm_mode_remove(struct drm_connector *connector, struct drm_display_mode *mode);
+extern void drm_mode_copy(struct drm_display_mode *dst, const struct drm_display_mode *src);
 extern struct drm_display_mode *drm_mode_duplicate(struct drm_device *dev,
 						   const struct drm_display_mode *mode);
 extern void drm_mode_debug_printmodeline(struct drm_display_mode *mode);