diff --git a/spec/datadog/tracing/integration_spec.rb b/spec/datadog/tracing/integration_spec.rb
index 9b6b88d251..52737af434 100644
--- a/spec/datadog/tracing/integration_spec.rb
+++ b/spec/datadog/tracing/integration_spec.rb
@@ -595,6 +595,13 @@ def agent_receives_span_step3(previous_success)
           span.service = 'my.service'
         end
 
+        # The background worker flushes nearly instantly (DEFAULT_FLUSH_INTERVAL
+        # is stubbed to 0), so the trace is almost always already flushed before
+        # shutdown threads start. Make that deterministic to avoid flakiness when
+        # the 1-second DEFAULT_SHUTDOWN_TIMEOUT is occasionally too short for the
+        # HTTP round-trip under CI load.
+        try_wait_until { tracer.writer.stats[:traces_flushed] >= 1 }
+
         threads = Array.new(10) do
           Thread.new { tracer.shutdown! }
         end