diff --git a/tests/Microsoft.Identity.Web.Test/L1L2CacheTests.cs b/tests/Microsoft.Identity.Web.Test/L1L2CacheTests.cs
index ca56e0f62..eb5395c84 100644
--- a/tests/Microsoft.Identity.Web.Test/L1L2CacheTests.cs
+++ b/tests/Microsoft.Identity.Web.Test/L1L2CacheTests.cs
@@ -16,6 +16,7 @@
 
 namespace Microsoft.Identity.Web.Test
 {
+    [CollectionDefinition(nameof(L1L2CacheTests), DisableParallelization = true)]
     public class L1L2CacheTests
     {
         private const string DefaultCacheKey = "default-key";
@@ -51,12 +52,12 @@ public async Task WriteCache_WritesInL1L2_TestAsync(bool enableAsyncL2Write)
             Assert.Empty(L2Cache._dict);
 
             // Act
-            TestDistributedCache.ResetEvent.Reset();
+            L2Cache.ResetEvent.Reset();
             await _testCacheAdapter.TestWriteCacheBytesAsync(DefaultCacheKey, cache);
 
             // Assert
             Assert.Equal(1, _testCacheAdapter._memoryCache.Count);
-            TestDistributedCache.ResetEvent.Wait();
+            L2Cache.ResetEvent.Wait();
             Assert.Single(L2Cache._dict);
         }
 
@@ -168,12 +169,12 @@ private async Task CreateL1L2TestWithSerializerHintsAsync(
             cacheSerializerHints.SuggestedCacheExpiry = dateTimeOffset;
 
             // Act
-            TestDistributedCache.ResetEvent.Reset();
+            L2Cache.ResetEvent.Reset();
             await _testCacheAdapter.TestWriteCacheBytesAsync(DefaultCacheKey, cache, cacheSerializerHints);
 
             // Assert
             Assert.Equal(memoryCacheExpectedCount, _testCacheAdapter._memoryCache.Count);
-            TestDistributedCache.ResetEvent.Wait();
+            L2Cache.ResetEvent.Wait();
             Assert.Single(L2Cache._dict);
         }
 
diff --git a/tests/Microsoft.Identity.Web.Test/TestDistributedCache.cs b/tests/Microsoft.Identity.Web.Test/TestDistributedCache.cs
index ab4216402..5e05d1645 100644
--- a/tests/Microsoft.Identity.Web.Test/TestDistributedCache.cs
+++ b/tests/Microsoft.Identity.Web.Test/TestDistributedCache.cs
@@ -11,7 +11,7 @@ namespace Microsoft.Identity.Web.Test
     public class TestDistributedCache : IDistributedCache
     {
         internal readonly ConcurrentDictionary<string, Entry> _dict = new ConcurrentDictionary<string, Entry>();
-        internal static ManualResetEventSlim ResetEvent { get; set; } = new ManualResetEventSlim(initialState: false);
+        internal ManualResetEventSlim ResetEvent { get; set; } = new ManualResetEventSlim(initialState: false);
 
         public byte[]? Get(string key)
         {
diff --git a/tests/Microsoft.Identity.Web.Test/TestTokenAcquisitionHost.cs b/tests/Microsoft.Identity.Web.Test/TestTokenAcquisitionHost.cs
index 6f0f07eb1..654cea51f 100644
--- a/tests/Microsoft.Identity.Web.Test/TestTokenAcquisitionHost.cs
+++ b/tests/Microsoft.Identity.Web.Test/TestTokenAcquisitionHost.cs
@@ -13,6 +13,8 @@ public class TestTokenAcquisitionHost
         [Fact]
         public void TestTokenAcquisitionHostNotAspNetCore()
         {
+            TokenAcquirerFactory.ResetDefaultInstance();
+
             // When not adding Services.AddAuthentication, the host should be 
             TokenAcquirerFactory tokenAcquirerFactory = TokenAcquirerFactory.GetDefaultInstance();
             var host = tokenAcquirerFactory.Services.First(s => s.ServiceType.FullName == "Microsoft.Identity.Web.ITokenAcquisitionHost");