diff --git a/test/Microsoft.SqlTools.ServiceLayer.Test.Common/MemoryFileSystem.cs b/test/Microsoft.SqlTools.ServiceLayer.Test.Common/MemoryFileSystem.cs
index e0cbe3ab..0369cbc3 100644
--- a/test/Microsoft.SqlTools.ServiceLayer.Test.Common/MemoryFileSystem.cs
+++ b/test/Microsoft.SqlTools.ServiceLayer.Test.Common/MemoryFileSystem.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
 using Microsoft.SqlTools.ServiceLayer.QueryExecution.DataStorage;
@@ -12,17 +13,17 @@ namespace Microsoft.SqlTools.ServiceLayer.Test.Common
 
         public static IFileStreamFactory GetFileStreamFactory()
         {
-            return GetFileStreamFactory(new Dictionary<string, byte[]>());
+            return GetFileStreamFactory(new ConcurrentDictionary<string, byte[]>());
         }
 
-        public static IFileStreamFactory GetFileStreamFactory(Dictionary<string, byte[]> storage)
+        public static IFileStreamFactory GetFileStreamFactory(ConcurrentDictionary<string, byte[]> storage)
         {
             Mock<IFileStreamFactory> mock = new Mock<IFileStreamFactory>();
             mock.Setup(fsf => fsf.CreateFile())
                 .Returns(() =>
                 {
                     string fileName = Guid.NewGuid().ToString();
-                    storage.Add(fileName, new byte[8192]);
+                    storage.TryAdd(fileName, new byte[8192]);
                     return fileName;
                 });
             mock.Setup(fsf => fsf.GetReader(It.IsAny<string>()))
diff --git a/test/Microsoft.SqlTools.ServiceLayer.UnitTests/QueryExecution/Common.cs b/test/Microsoft.SqlTools.ServiceLayer.UnitTests/QueryExecution/Common.cs
index fd6b02d8..04487716 100644
--- a/test/Microsoft.SqlTools.ServiceLayer.UnitTests/QueryExecution/Common.cs
+++ b/test/Microsoft.SqlTools.ServiceLayer.UnitTests/QueryExecution/Common.cs
@@ -2,6 +2,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Data;
 using System.Data.Common;
@@ -212,10 +213,10 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.QueryExecution
 
         public static QueryExecutionService GetPrimedExecutionService(TestResultSet[] data,
             bool isConnected, bool throwOnRead, WorkspaceService<SqlToolsSettings> workspaceService,
-            out Dictionary<string, byte[]> storage)
+            out ConcurrentDictionary<string, byte[]> storage)
         {
             // Create a place for the temp "files" to be written
-            storage = new Dictionary<string, byte[]>();
+            storage = new ConcurrentDictionary<string, byte[]>();
 
             // Mock the connection service
             var connectionService = new Mock<ConnectionService>();
@@ -231,7 +232,7 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.QueryExecution
 
         public static QueryExecutionService GetPrimedExecutionService(TestResultSet[] data, bool isConnected, bool throwOnRead, WorkspaceService<SqlToolsSettings> workspaceService)
         {
-            Dictionary<string, byte[]> storage;
+            ConcurrentDictionary<string, byte[]> storage;
             return GetPrimedExecutionService(data, isConnected, throwOnRead, workspaceService, out storage);
         }
 
diff --git a/test/Microsoft.SqlTools.ServiceLayer.UnitTests/QueryExecution/SaveResults/ServiceIntegrationTests.cs b/test/Microsoft.SqlTools.ServiceLayer.UnitTests/QueryExecution/SaveResults/ServiceIntegrationTests.cs
index 33d3d28c..4ae8c36f 100644
--- a/test/Microsoft.SqlTools.ServiceLayer.UnitTests/QueryExecution/SaveResults/ServiceIntegrationTests.cs
+++ b/test/Microsoft.SqlTools.ServiceLayer.UnitTests/QueryExecution/SaveResults/ServiceIntegrationTests.cs
@@ -3,6 +3,7 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 //
 
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
 using System.Threading.Tasks;
@@ -52,7 +53,7 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.QueryExecution.SaveResults
             // Given: 
             // ... A working query and workspace service
             WorkspaceService<SqlToolsSettings> ws = Common.GetPrimedWorkspaceService(Constants.StandardQuery);
-            Dictionary<string, byte[]> storage;
+            ConcurrentDictionary<string, byte[]> storage;
             QueryExecutionService qes = Common.GetPrimedExecutionService(Common.ExecutionPlanTestDataSet, true, false, ws, out storage);
 
             // ... The query execution service has executed a query with results
@@ -97,7 +98,7 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.QueryExecution.SaveResults
             // Given: 
             // ... A working query and workspace service
             WorkspaceService<SqlToolsSettings> ws = Common.GetPrimedWorkspaceService(Constants.StandardQuery);
-            Dictionary<string, byte[]> storage;
+            ConcurrentDictionary<string, byte[]> storage;
             QueryExecutionService qes = Common.GetPrimedExecutionService(Common.ExecutionPlanTestDataSet, true, false, ws, out storage);
 
             // ... The query execution service has executed a query with results
@@ -164,7 +165,7 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.QueryExecution.SaveResults
             // Given: 
             // ... A working query and workspace service
             WorkspaceService<SqlToolsSettings> ws = Common.GetPrimedWorkspaceService(Constants.StandardQuery);
-            Dictionary<string, byte[]> storage;
+            ConcurrentDictionary<string, byte[]> storage;
             QueryExecutionService qes = Common.GetPrimedExecutionService(Common.StandardTestDataSet, true, false, ws, out storage);
 
             // ... The query execution service has executed a query with results
@@ -207,7 +208,7 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.QueryExecution.SaveResults
             // Given: 
             // ... A working query and workspace service
             WorkspaceService<SqlToolsSettings> ws = Common.GetPrimedWorkspaceService(Constants.StandardQuery);
-            Dictionary<string, byte[]> storage;
+            ConcurrentDictionary<string, byte[]> storage;
             QueryExecutionService qes = Common.GetPrimedExecutionService(Common.StandardTestDataSet, true, false, ws, out storage);
 
             // ... The query execution service has executed a query with results
@@ -273,7 +274,7 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.QueryExecution.SaveResults
             // Given: 
             // ... A working query and workspace service
             WorkspaceService<SqlToolsSettings> ws = Common.GetPrimedWorkspaceService(Constants.StandardQuery);
-            Dictionary<string, byte[]> storage;
+            ConcurrentDictionary<string, byte[]> storage;
             QueryExecutionService qes = Common.GetPrimedExecutionService(Common.StandardTestDataSet, true, false, ws, out storage);
 
             // ... The query execution service has executed a query with results
@@ -316,7 +317,7 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.QueryExecution.SaveResults
             // Given: 
             // ... A working query and workspace service
             WorkspaceService<SqlToolsSettings> ws = Common.GetPrimedWorkspaceService(Constants.StandardQuery);
-            Dictionary<string, byte[]> storage;
+            ConcurrentDictionary<string, byte[]> storage;
             QueryExecutionService qes = Common.GetPrimedExecutionService(Common.StandardTestDataSet, true, false, ws, out storage);
 
             // ... The query execution service has executed a query with results