diff --git a/xf86drmMode.c b/xf86drmMode.c
index 22a8a7c2..65d54d78 100644
--- a/xf86drmMode.c
+++ b/xf86drmMode.c
@@ -1004,8 +1004,8 @@ drm_public int drmModeCrtcGetGamma(int fd, uint32_t crtc_id, uint32_t size,
 }
 
 drm_public int drmModeCrtcSetGamma(int fd, uint32_t crtc_id, uint32_t size,
-								   uint16_t *red, uint16_t *green,
-								   uint16_t *blue)
+								   const uint16_t *red, const uint16_t *green,
+								   const uint16_t *blue)
 {
 	struct drm_mode_crtc_lut l;
 
diff --git a/xf86drmMode.h b/xf86drmMode.h
index d911c9a1..b6410ab8 100644
--- a/xf86drmMode.h
+++ b/xf86drmMode.h
@@ -416,7 +416,7 @@ extern int drmModeConnectorSetProperty(int fd, uint32_t connector_id, uint32_t p
 extern int drmCheckModesettingSupported(const char *busid);
 
 extern int drmModeCrtcSetGamma(int fd, uint32_t crtc_id, uint32_t size,
-			       uint16_t *red, uint16_t *green, uint16_t *blue);
+			       const uint16_t *red, const uint16_t *green, const uint16_t *blue);
 extern int drmModeCrtcGetGamma(int fd, uint32_t crtc_id, uint32_t size,
 			       uint16_t *red, uint16_t *green, uint16_t *blue);
 extern int drmModePageFlip(int fd, uint32_t crtc_id, uint32_t fb_id,