diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h
index 0c6f0e1..0b0d236 100644
--- a/include/drm/drm_crtc_helper.h
+++ b/include/drm/drm_crtc_helper.h
@@ -54,13 +54,13 @@
 			   struct drm_display_mode *mode,
 			   struct drm_display_mode *adjusted_mode);
 	/* Actually set the mode */
-	void (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
-			 struct drm_display_mode *adjusted_mode, int x, int y,
-			 struct drm_framebuffer *old_fb);
+	int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
+			struct drm_display_mode *adjusted_mode, int x, int y,
+			struct drm_framebuffer *old_fb);
 
 	/* Move the crtc on the current fb to the given position *optional* */
-	void (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
-			      struct drm_framebuffer *old_fb);
+	int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
+			     struct drm_framebuffer *old_fb);
 };
 
 struct drm_encoder_helper_funcs {