diff --git a/proxy/pool.py b/proxy/pool.py
index 587aeb1..e2ed7db 100644
--- a/proxy/pool.py
+++ b/proxy/pool.py
@@ -149,6 +149,8 @@ class _WsPool:
                     log.debug(
                         "WS pool rotated DC%d%s: %d stale, %d ready",
                         dc, 'm' if is_media else '', len(expired), len(bucket))
+
+                if len(bucket) < proxy_config.pool_size:
                     self._schedule_refill(key, target_ip, domains)
         finally:
             if self._rotating.get(key) is asyncio.current_task():
diff --git a/tests/test_pool.py b/tests/test_pool.py
new file mode 100644
index 0000000..cad8bea
--- /dev/null
+++ b/tests/test_pool.py
@@ -0,0 +1,53 @@
+import time
+import unittest
+
+from collections import deque
+from types import SimpleNamespace
+from unittest import mock
+
+from proxy.config import proxy_config
+from proxy.pool import _WsPool
+
+
+class _StopRotation(Exception):
+    pass
+
+
+def _open_ws():
+    transport = SimpleNamespace(is_closing=lambda: False)
+    writer = SimpleNamespace(transport=transport)
+    return SimpleNamespace(_closed=False, writer=writer)
+
+
+class WsPoolRotationTest(unittest.IsolatedAsyncioTestCase):
+    async def test_refills_partially_populated_bucket(self):
+        pool = _WsPool()
+        key = (2, False)
+        pool._idle[key] = deque([
+            (_open_ws(), time.monotonic()),
+            (_open_ws(), time.monotonic()),
+        ])
+        sleep_calls = 0
+
+        async def stop_after_one_iteration(_delay):
+            nonlocal sleep_calls
+            sleep_calls += 1
+            if sleep_calls > 1:
+                raise _StopRotation
+
+        with mock.patch.object(proxy_config, 'pool_size', 4):
+            with mock.patch(
+                    'proxy.pool.asyncio.sleep',
+                    side_effect=stop_after_one_iteration):
+                with mock.patch.object(
+                        pool, '_schedule_refill') as schedule_refill:
+                    with self.assertRaises(_StopRotation):
+                        await pool._rotate(
+                            key, '149.154.167.220', ['example.com'])
+
+        schedule_refill.assert_called_once_with(
+            key, '149.154.167.220', ['example.com'])
+
+
+if __name__ == '__main__':
+    unittest.main()