diff --git a/src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs b/src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
index 0e8cfc240ceb94..7fee0affc047c3 100644
--- a/src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
+++ b/src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.MaxResponseHeadersLength.cs
@@ -73,7 +73,7 @@ await LoopbackServerFactory.CreateClientAndServerAsync(async uri =>
         [InlineData(15)]
         public async Task LargeSingleHeader_ThrowsException(int maxResponseHeadersLength)
         {
-            var semaphore = new SemaphoreSlim(0);
+            using var ce = new CountdownEvent(2);
             using HttpClientHandler handler = CreateHttpClientHandler();
             handler.MaxResponseHeadersLength = maxResponseHeadersLength;
 
@@ -86,7 +86,8 @@ await LoopbackServerFactory.CreateClientAndServerAsync(async uri =>
                 {
                     Assert.Contains((handler.MaxResponseHeadersLength * 1024).ToString(), e.ToString());
                 }
-                await semaphore.WaitAsync();
+                ce.Signal();
+                ce.Wait(TestHelper.PassingTestTimeout);
             },
             async server =>
             {
@@ -105,7 +106,8 @@ await LoopbackServerFactory.CreateClientAndServerAsync(async uri =>
 #endif
                 finally
                 {
-                    semaphore.Release();
+                    ce.Signal();
+                    ce.Wait(TestHelper.PassingTestTimeout);
                     await connection.DisposeAsync();
                 }
             });
@@ -119,7 +121,7 @@ await LoopbackServerFactory.CreateClientAndServerAsync(async uri =>
         [InlineData(int.MaxValue / 800, 100 * 1024)] // Capped at int.MaxValue
         public async Task ThresholdExceeded_ThrowsException(int? maxResponseHeadersLength, int headersLengthEstimate)
         {
-            var semaphore = new SemaphoreSlim(0);
+            using var ce = new CountdownEvent(2);
             await LoopbackServerFactory.CreateClientAndServerAsync(async uri =>
             {
                 using HttpClientHandler handler = CreateHttpClientHandler();
@@ -143,7 +145,8 @@ await LoopbackServerFactory.CreateClientAndServerAsync(async uri =>
                         Assert.Contains((handler.MaxResponseHeadersLength * 1024).ToString(), e.ToString());
                     }
                 }
-                await semaphore.WaitAsync();
+                ce.Signal();
+                ce.Wait(TestHelper.PassingTestTimeout);
             },
             async server =>
             {
@@ -168,7 +171,8 @@ await LoopbackServerFactory.CreateClientAndServerAsync(async uri =>
 #endif
                 finally
                 {
-                    semaphore.Release();
+                    ce.Signal();
+                    ce.Wait(TestHelper.PassingTestTimeout);
                     await connection.DisposeAsync();
                 }
             });