diff --git a/sm3/kdf_mult_asm.go b/sm3/kdf_mult_asm.go
index 520867c..3b1ef68 100644
--- a/sm3/kdf_mult_asm.go
+++ b/sm3/kdf_mult_asm.go
@@ -30,8 +30,7 @@ func copyResult(result []byte, dig *[8]uint32) {
 
 // state || words
 // 1216 = 68 * 4 * 4 + 8 * 4 * 4 = 76 * 16
-// 8 * 16 = 128
-const preallocSize = 1344
+const preallocSize = 1216
 
 func kdfBy4(baseMD *digest, keyLen int, limit int) []byte {
 	if limit < 4 {
diff --git a/sm3/sm3blocks_arm64.s b/sm3/sm3blocks_arm64.s
index ec35b77..c529810 100644
--- a/sm3/sm3blocks_arm64.s
+++ b/sm3/sm3blocks_arm64.s
@@ -190,7 +190,6 @@ TEXT ·blockMultBy4(SB), NOSPLIT, $0
 	MOVD statePtr, wordStart
 	VST1.P [a.S4, b.S4, c.S4, d.S4], 64(wordStart)
 	VST1.P [e.S4, f.S4, g.S4, h.S4], 64(wordStart)
-	MOVD wordStart, wordPtr
 
 	MOVD.P 8(srcPtrPtr), srcPtr1
 	MOVD.P 8(srcPtrPtr), srcPtr2
@@ -198,6 +197,7 @@ TEXT ·blockMultBy4(SB), NOSPLIT, $0
 	MOVD (srcPtrPtr), srcPtr4
 
 loop:
+	MOVD wordStart, wordPtr
 	// load message block
 	prepare4Words
 	prepare4Words