diff --git a/src/quic_cc_cubic.c b/src/quic_cc_cubic.c
index 791987c97..0ed4a325e 100644
--- a/src/quic_cc_cubic.c
+++ b/src/quic_cc_cubic.c
@@ -138,7 +138,7 @@ static inline void quic_cubic_update(struct quic_cc *cc, uint32_t acked)
 		goto leave;
 	}
 
-	delta = path->mtu * ((CUBIC_C * diff * diff * diff) >> (10 + 3 * TIME_SCALE_FACTOR_SHIFT));
+	delta = path->mtu * ((CUBIC_C * diff * diff * diff) >> (CUBIC_BETA_SCALE_SHIFT + 3 * TIME_SCALE_FACTOR_SHIFT));
 	if (t < c->K)
 		target = c->origin_point - delta;
 	else