diff --git a/drivers/gpu/drm/imx/imx-drm.h b/drivers/gpu/drm/imx/imx-drm.h
index 83284b4..71cf6d9 100644
--- a/drivers/gpu/drm/imx/imx-drm.h
+++ b/drivers/gpu/drm/imx/imx-drm.h
@@ -13,7 +13,7 @@
 struct imx_drm_crtc;
 struct platform_device;
 
-int imx_drm_crtc_id(struct imx_drm_crtc *crtc);
+unsigned int imx_drm_crtc_id(struct imx_drm_crtc *crtc);
 
 struct imx_drm_crtc_helper_funcs {
 	int (*enable_vblank)(struct drm_crtc *crtc);