diff --git a/salsa20/salsa/salsa2020_amd64.s b/salsa20/salsa/salsa2020_amd64.s
index 6e1df96..9c4ae96 100644
--- a/salsa20/salsa/salsa2020_amd64.s
+++ b/salsa20/salsa/salsa2020_amd64.s
@@ -16,10 +16,10 @@ TEXT ·salsa2020XORKeyStream(SB),0,$512-40
 	MOVQ key+32(FP),R8
 
 	MOVQ SP,R11
-	MOVQ $31,R9
-	NOTQ R9
-	ANDQ R9,SP
-	ADDQ $32,SP
+	MOVQ SP,R9
+	ADDQ $31, R9
+	ANDQ $~31, R9
+	MOVQ R9, SP
 
 	MOVQ R11,352(SP)
 	MOVQ R12,360(SP)