diff --git a/src/transport_layer/etcp_bbr.c b/src/transport_layer/etcp_bbr.c
index f6b8a33a..e0f580d9 100644
--- a/src/transport_layer/etcp_bbr.c
+++ b/src/transport_layer/etcp_bbr.c
@@ -414,7 +414,8 @@ static void bbr_probe_inflight_hi_upward(struct bbr* bbr, const struct bbr_rate_
         bbr->bw_probe_up_cnt > 0) {
         delta = bbr->bw_probe_up_acks / bbr->bw_probe_up_cnt;
         bbr->bw_probe_up_acks -= delta * bbr->bw_probe_up_cnt;
-        bbr->inflight_hi += delta;
+        uint64_t raised = (uint64_t)bbr->inflight_hi + delta;
+        bbr->inflight_hi = raised > UINT32_MAX ? UINT32_MAX : (uint32_t)raised;
         bbr->try_fast_path = 0;
     }
     if (bbr->round_start)
@@ -749,19 +750,20 @@ static void bbr_set_cwnd(struct bbr* bbr, const struct bbr_rate_sample* rs,
     if (!acked)
         goto done;
 
-    target_cwnd = bbr_bdp(bbr, bw, gain, mss);
-    target_cwnd += bbr_ack_aggregation_cwnd(bbr, mss);
+    uint64_t target = (uint64_t)bbr_bdp(bbr, bw, gain, mss) + bbr_ack_aggregation_cwnd(bbr, mss);
+    target_cwnd = target > UINT32_MAX ? UINT32_MAX : (uint32_t)target;
     target_cwnd = bbr_quantization_budget(bbr, target_cwnd, mss);
+    uint64_t grown = (uint64_t)local_cwnd + acked;
 
     bbr->try_fast_path = 0;
     if (bbr->full_bw_reached) {
-        local_cwnd += acked;
+        local_cwnd = grown > UINT32_MAX ? UINT32_MAX : (uint32_t)grown;
         if (local_cwnd >= target_cwnd) {
             local_cwnd = target_cwnd;
             bbr->try_fast_path = 1;
         }
     } else if (local_cwnd < target_cwnd || local_cwnd < 2 * (uint32_t)bbr->init_cwnd * mss) {
-        local_cwnd += acked;
+        local_cwnd = grown > UINT32_MAX ? UINT32_MAX : (uint32_t)grown;
     } else {
         bbr->try_fast_path = 1;
     }
diff --git a/tests/test_etcp_bbr.c b/tests/test_etcp_bbr.c
index fe46902e..095943d2 100644
--- a/tests/test_etcp_bbr.c
+++ b/tests/test_etcp_bbr.c
@@ -127,6 +127,21 @@ static int test_large_ack_aggregation(void) {
     PASS(); return 0;
 }
 
+/* Большой BDP и прибавление ACK не должны оборачивать окно до нескольких пакетов. */
+static int test_cwnd_saturation(void) {
+    MSEG("large BDP and acknowledged bytes saturate cwnd");
+    struct bbr s = { .now_tb = 10000 }; bbr_init(&s);
+    s.mode = BBR_PROBE_BW; s.full_bw_reached = 1; s.cycle_idx = BBR_BW_PROBE_CRUISE;
+    s.cycle_mstamp_tb = s.now_tb; s.probe_wait_us = 2000000;
+    uint32_t cwnd = UINT32_MAX - 500, pacing = 0;
+    struct bbr_rate_sample rs = { .delivered = 10000, .interval_us = 1, .rtt_us = 1000000,
+        .acked_sacked = 1000, .tx_in_flight = UINT32_MAX - 500 };
+    bbr_main(&s, &rs, &cwnd, &pacing, 1400, UINT32_MAX - 500, 0);
+    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "BBR saturated window: cwnd=%u expected=%u", cwnd, UINT32_MAX);
+    if (cwnd != UINT32_MAX) FAIL("BDP plus ACK and cwnd plus ACK must saturate, not wrap");
+    PASS(); return 0;
+}
+
 static int test_init(void)
 {
     MSEG("bbr_init — startup mode");
@@ -246,6 +261,7 @@ int main(void)
     test_probe_growth_bytes();
     test_probe_packet_budget();
     test_large_ack_aggregation();
+    test_cwnd_saturation();
     test_init();
     test_startup_growth();
     test_full_bw();