diff --git a/internal/subtle/xor_s390x.s b/internal/subtle/xor_s390x.s
index 0e3f633..764a810 100644
--- a/internal/subtle/xor_s390x.s
+++ b/internal/subtle/xor_s390x.s
@@ -14,15 +14,26 @@ TEXT ·xorBytes(SB),NOSPLIT,$0-32
 	MOVD	n+24(FP), R4
 
 	MOVD	$0, R5
+	CMPBLT	R4, $16, less_than16
+
+loop16b:
+	VL 0(R2)(R5*1), V0
+	VL 0(R3)(R5*1), V1
+	VX V0, V1, V2
+	VST V2, 0(R1)(R5*1)
+	LAY	16(R5), R5
+	SUB	$16, R4
+	CMPBGE	R4, $16, loop16b
+
+less_than16:
 	CMPBLT	R4, $8, tail
-loop:
 	MOVD	0(R2)(R5*1), R7
 	MOVD	0(R3)(R5*1), R8
 	XOR	R7, R8
 	MOVD	R8, 0(R1)(R5*1)
 	LAY	8(R5), R5
 	SUB	$8, R4
-	CMPBGE	R4, $8, loop
+
 tail:
 	CMPBEQ	R4, $0, done
 	MOVB	0(R2)(R5*1), R7
@@ -32,5 +43,6 @@ tail:
 	LAY	1(R5), R5
 	SUB	$1, R4
 	BR	tail
+
 done:
 	RET