diff --git a/tests/test_cubic.py b/tests/test_cubic.py
index 39750c8a5..6252be188 100644
--- a/tests/test_cubic.py
+++ b/tests/test_cubic.py
@@ -1,5 +1,4 @@
 from aioquic.quic.congestion.cubic import CubicCongestionControl, K_CUBIC_C, K_CUBIC_LOSS_REDUCTION_FACTOR, QuicSentPacket
-from aioquic.quic.congestion import K_MAX_DATAGRAM_SIZE
 import unittest
 
 def W_cubic(t, K, W_max):
@@ -9,6 +8,11 @@ def cube_root(x):
     if (x < 0): return -((-x)**(1/3))
     else: return x**(1/3)
 
+class RecoveryStaticRtt:
+    def __init__(self):
+        self._rtt_smoothed = 0
+
+
 class CubicTests(unittest.TestCase):
 
     def test_congestion_avoidance(self):
@@ -16,6 +20,8 @@ def test_congestion_avoidance(self):
         Check if the cubic implementation respects the mathematical formula defined in the rfc 9438
         """
 
+        max_datagram_size = 1440
+
         n = 400  # number of ms to check
 
         W_max = 5  # starting W_max
@@ -27,25 +33,25 @@ def test_congestion_avoidance(self):
         test_range = range(n)
 
         for i in test_range:
-            correct.append(W_cubic(i/1000, K, W_max) * K_MAX_DATAGRAM_SIZE)
+            correct.append(W_cubic(i/1000, K, W_max) * max_datagram_size)
 
-        cubic = CubicCongestionControl()
-        cubic._W_max = W_max * K_MAX_DATAGRAM_SIZE
+        cubic = CubicCongestionControl(max_datagram_size, RecoveryStaticRtt())
+        cubic._W_max = W_max * max_datagram_size
         cubic._starting_congestion_avoidance = True
-        cubic.congestion_window = cwnd * K_MAX_DATAGRAM_SIZE
-        cubic.slow_start.ssthresh = cubic.congestion_window
+        cubic.congestion_window = cwnd * max_datagram_size
+        cubic.ssthresh = cubic.congestion_window
         cubic._W_est = 0
 
         results = []
         for i in test_range:
-            cwnd = cubic.congestion_window // K_MAX_DATAGRAM_SIZE # number of segments
+            cwnd = cubic.congestion_window // max_datagram_size # number of segments
 
             # simulate the reception of cwnd packets (a full window of acks)
             for _ in range(int(cwnd)):
                 packet = QuicSentPacket(None, True, True, True, 0, 0)
                 packet.sent_bytes = 0  # won't affect results
-                rtt = 0
-                cubic.on_packet_acked_timed(packet, i/1000, rtt)
+
+                cubic.on_packet_acked(packet, i/1000)
 
             results.append(cubic.congestion_window)