diff --git a/src/libraries/System.Diagnostics.Tracing/tests/BasicEventSourceTest/TestsManifestGeneration.Etw.cs b/src/libraries/System.Diagnostics.Tracing/tests/BasicEventSourceTest/TestsManifestGeneration.Etw.cs
index 4fd7f3e928ec7..bbe134bda23ae 100644
--- a/src/libraries/System.Diagnostics.Tracing/tests/BasicEventSourceTest/TestsManifestGeneration.Etw.cs
+++ b/src/libraries/System.Diagnostics.Tracing/tests/BasicEventSourceTest/TestsManifestGeneration.Etw.cs
@@ -54,6 +54,11 @@ public void Test_EventSource_EtwManifestGeneration()
                     Thread.Sleep(TimeSpan.FromSeconds(5));
 
                     tracesession.Flush();
+
+                    // Sleep after requesting flush to ensure that the manifest payload generated
+                    // is fully written to the etl file.
+                    Thread.Sleep(TimeSpan.FromSeconds(5));
+
                     tracesession.DisableProvider("SimpleEventSource");
                     tracesession.Dispose();
 
@@ -87,6 +92,10 @@ public void Test_EventSource_EtwManifestGenerationRollover()
 
                     tracesession.Flush();
 
+                    // Sleep after requesting flush to ensure that the manifest payload generated
+                    // is fully written to the etl file.
+                    Thread.Sleep(TimeSpan.FromSeconds(5));
+
                     tracesession.SetFileName(rolloverFile);
 
                     Thread.Sleep(TimeSpan.FromSeconds(5));