diff --git a/core/src/test/java/io/questdb/client/test/cutlass/qwp/client/sf/cursor/SenderErrorDispatcherTest.java b/core/src/test/java/io/questdb/client/test/cutlass/qwp/client/sf/cursor/SenderErrorDispatcherTest.java
index 957e36d4..f8d45c8e 100644
--- a/core/src/test/java/io/questdb/client/test/cutlass/qwp/client/sf/cursor/SenderErrorDispatcherTest.java
+++ b/core/src/test/java/io/questdb/client/test/cutlass/qwp/client/sf/cursor/SenderErrorDispatcherTest.java
@@ -101,11 +101,13 @@ public void testFullInboxDropsOldestAndCounts() throws Exception {
         // Spec sf-client.md section 14.6: on overflow, drop the OLDEST entry
         // and admit the new one. The latest entry is always the most
         // informative, so the FIFO head loses, not the new arrival.
+        CountDownLatch handlerEntered = new CountDownLatch(1);
         CountDownLatch unblock = new CountDownLatch(1);
         List<SenderError> received = new ArrayList<>();
         Object lock = new Object();
         CountDownLatch allDelivered = new CountDownLatch(5);
         try (SenderErrorDispatcher d = new SenderErrorDispatcher(err -> {
+            handlerEntered.countDown();
             try {
                 unblock.await();
             } catch (InterruptedException ignored) {
@@ -116,13 +118,12 @@ public void testFullInboxDropsOldestAndCounts() throws Exception {
             }
             allDelivered.countDown();
         }, /*capacity=*/ 4)) {
-            // First offer starts the dispatcher and lands in the handler
-            // immediately (and blocks there). Now we can fill the bounded
-            // inbox to capacity, then overflow.
+            // First offer starts the dispatcher. Wait until it lands in the
+            // handler and blocks there before filling the bounded inbox and
+            // overflowing it.
             Assert.assertTrue(d.offer(buildError(0)));
-            // Give the dispatcher a moment to take the head into the
-            // handler so subsequent offers don't get an extra slot.
-            TimeUnit.MILLISECONDS.sleep(50);
+            Assert.assertTrue("first error should reach handler within 5s",
+                    handlerEntered.await(5, TimeUnit.SECONDS));
             for (int i = 1; i <= 4; i++) {
                 Assert.assertTrue("inbox should accept offer " + i,
                         d.offer(buildError(i)));