diff --git a/drivers/video/fsl-diu-fb.c b/drivers/video/fsl-diu-fb.c
index 19bfbf5bb980..3776949d6183 100644
--- a/drivers/video/fsl-diu-fb.c
+++ b/drivers/video/fsl-diu-fb.c
@@ -655,7 +655,7 @@ static void set_fix(struct fb_info *info)
 	struct fb_var_screeninfo *var = &info->var;
 	struct mfb_info *mfbi = info->par;
 
-	strncpy(fix->id, mfbi->id, strlen(mfbi->id));
+	strncpy(fix->id, mfbi->id, sizeof(fix->id));
 	fix->line_length = var->xres_virtual * var->bits_per_pixel / 8;
 	fix->type = FB_TYPE_PACKED_PIXELS;
 	fix->accel = FB_ACCEL_NONE;