diff --git a/SM2-MFMM-(2).md b/SM2-MFMM-(2).md
index cd8cccc..9e8a587 100644
--- a/SM2-MFMM-(2).md
+++ b/SM2-MFMM-(2).md
@@ -104,17 +104,17 @@ $t_0=t_0 - a_1$
 	\ // First reduction step, [p3, p2, p1, p0] = [1, -0x100000000, 0, (1 - 0x100000000), -1]
 	MOVQ acc0, AX           \
 	MOVQ acc0, DX           \
-	MOVQ acc0, CX           \
 	SHLQ $32, AX            \  // AX = L(acc0 * 2^32), low part
 	SHRQ $32, DX            \  // DX = H(acc0 * 2^32), high part
 	\// calculate the negative part: [0, -0x100000000, 0, -0x100000000] * acc0
 	SUBQ AX, acc1            \ 
 	SBBQ DX, acc2            \
 	SBBQ AX, acc3            \
+	MOVQ acc0, AX            \
 	SBBQ DX, acc0            \
 	\ // calculate the positive part: [1, 0, 0, 1] * acc0 + [0, acc3, acc2, acc1], 
 	\ // due to (-1) * acc0 + acc0 == 0, so last lowest lamb 0 is dropped directly, no carry.
-	ADDQ CX, acc1          \ // acc1' = L (acc0 + acc1)
+	ADDQ AX, acc1          \ // acc1' = L (acc0 + acc1)
 	ADCQ $0, acc2            \ // acc2' = acc2 + carry1
 	ADCQ $0, acc3            \ // acc3' = acc3 + carry2
 	ADCQ $0, acc0            \ // acc0' = acc0 + carry3