diff --git a/crypto/aes/asm/aes-x86_64.pl b/crypto/aes/asm/aes-x86_64.pl
index 995448a11..da4253889 100755
--- a/crypto/aes/asm/aes-x86_64.pl
+++ b/crypto/aes/asm/aes-x86_64.pl
@@ -1634,6 +1634,7 @@ AES_cbc_encrypt:
 	push	%r15
 	pushfq
 	cld
+	mov	%r9d,%r9d	# clear upper half of enc
 
 	.picmeup $sbox
 	lea	AES_Te-.($sbox),$sbox