diff --git a/hw/xfree86/drivers/modesetting/drmmode_display.c b/hw/xfree86/drivers/modesetting/drmmode_display.c
index 52de242e2..e7652c2dd 100644
--- a/hw/xfree86/drivers/modesetting/drmmode_display.c
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.c
@@ -1927,7 +1927,9 @@ drmmode_set_gamma_lut(drmmode_crtc_private_ptr drmmode_crtc,
     }
 
     uint32_t blob_id;
-    if (drmModeCreatePropertyBlob(drmmode->fd, lut, sizeof(lut), &blob_id)) {
+    if (drmModeCreatePropertyBlob(drmmode->fd, lut,
+                                  sizeof(struct drm_color_lut) * size,
+                                  &blob_id)) {
         free(lut);
         return;
     }