diff --git a/cipher/cipher-gcm-armv8-aarch64-ce.S b/cipher/cipher-gcm-armv8-aarch64-ce.S
--- a/cipher/cipher-gcm-armv8-aarch64-ce.S
+++ b/cipher/cipher-gcm-armv8-aarch64-ce.S
@@ -385,6 +385,8 @@
 
   GET_DATA_POINTER(x2, .Lrconst)
 
+  eor vZZ.16b, vZZ.16b, vZZ.16b
+
   /* H¹ */
   ld1 {rh1.16b}, [x0]
   rbit rh1.16b, rh1.16b