diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index bb097b1644d8..07713d64debe 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -82,8 +82,7 @@ int save_i387_xstate(void __user *buf)
 	if (!access_ok(VERIFY_WRITE, buf, sig_xstate_size))
 		return -EACCES;
 
-	BUILD_BUG_ON(sizeof(struct user_i387_struct) !=
-			sizeof(tsk->thread.xstate->fxsave));
+	BUG_ON(sig_xstate_size < xstate_size);
 
 	if ((unsigned long)buf % 64)
 		printk("save_i387_xstate: bad fpstate %p\n", buf);