diff --git a/internal/sm2ec/p256_asm_s390x.s b/internal/sm2ec/p256_asm_s390x.s
index 69746f3..d00fd63 100644
--- a/internal/sm2ec/p256_asm_s390x.s
+++ b/internal/sm2ec/p256_asm_s390x.s
@@ -511,7 +511,7 @@ loop_select:
 	VAB  SEL2, ONE, SEL2
 	ADDW $1, COUNT
 	ADD  $64, P1ptr
-	CMPW COUNT, $65
+	CMPW COUNT, $33
 	BLT  loop_select
 	VST  X1H, 0(P3ptr)
 	VST  X1L, 16(P3ptr)