diff --git a/src/Microsoft.AspNet.Http/BufferingHelper.cs b/src/Microsoft.AspNet.Http/BufferingHelper.cs
index 3335203e29..47b08915c4 100644
--- a/src/Microsoft.AspNet.Http/BufferingHelper.cs
+++ b/src/Microsoft.AspNet.Http/BufferingHelper.cs
@@ -12,21 +12,30 @@ namespace Microsoft.AspNet.Http.Internal
     {
         internal const int DefaultBufferThreshold = 1024 * 30;
 
+        private readonly static Func<string> _getTempDirectory = () => TempDirectory;
+
+        private static string _tempDirectory;
+
         public static string TempDirectory
         {
             get
             {
-                // Look for folders in the following order.
-                var temp = Environment.GetEnvironmentVariable("ASPNET_TEMP") ??     // ASPNET_TEMP - User set temporary location.
-                           Path.GetTempPath();                                      // Fall back.
-
-                if (!Directory.Exists(temp))
+                if (_tempDirectory == null)
                 {
-                    // TODO: ???
-                    throw new DirectoryNotFoundException(temp);
+                    // Look for folders in the following order.
+                    var temp = Environment.GetEnvironmentVariable("ASPNET_TEMP") ??     // ASPNET_TEMP - User set temporary location.
+                               Path.GetTempPath();                                      // Fall back.
+
+                    if (!Directory.Exists(temp))
+                    {
+                        // TODO: ???
+                        throw new DirectoryNotFoundException(temp);
+                    }
+
+                    _tempDirectory = temp;
                 }
 
-                return temp;
+                return _tempDirectory;
             }
         }
 
@@ -37,7 +46,7 @@ namespace Microsoft.AspNet.Http.Internal
             {
                 // TODO: Register this buffer for disposal at the end of the request to ensure the temp file is deleted.
                 //  Otherwise it won't get deleted until GC closes the stream.
-                request.Body = new FileBufferingReadStream(body, bufferThreshold, TempDirectory);
+                request.Body = new FileBufferingReadStream(body, bufferThreshold, _getTempDirectory);
             }
             return request;
         }
diff --git a/src/Microsoft.AspNet.WebUtilities/FileBufferingReadStream.cs b/src/Microsoft.AspNet.WebUtilities/FileBufferingReadStream.cs
index b6df361dc4..9bed427578 100644
--- a/src/Microsoft.AspNet.WebUtilities/FileBufferingReadStream.cs
+++ b/src/Microsoft.AspNet.WebUtilities/FileBufferingReadStream.cs
@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Diagnostics;
 using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
@@ -18,7 +19,8 @@ namespace Microsoft.AspNet.WebUtilities
     {
         private readonly Stream _inner;
         private readonly int _memoryThreshold;
-        private readonly string _tempFileDirectory;
+        private string _tempFileDirectory;
+        private readonly Func<string> _tempFileDirectoryAccessor;
 
         private Stream _buffer = new MemoryStream(); // TODO: We could have a more efficiently expanding buffer stream.
         private bool _inMemory = true;
@@ -26,6 +28,17 @@ namespace Microsoft.AspNet.WebUtilities
 
         private bool _disposed;
 
+        // TODO: allow for an optional buffer size limit to prevent filling hard disks. 1gb?
+        public FileBufferingReadStream(
+            [NotNull] Stream inner,
+            int memoryThreshold,
+            [NotNull] Func<string> tempFileDirectoryAccessor)
+        {
+            _inner = inner;
+            _memoryThreshold = memoryThreshold;
+            _tempFileDirectoryAccessor = tempFileDirectoryAccessor;
+        }
+
         // TODO: allow for an optional buffer size limit to prevent filling hard disks. 1gb?
         public FileBufferingReadStream([NotNull] Stream inner, int memoryThreshold, [NotNull] string tempFileDirectory)
         {
@@ -88,6 +101,13 @@ namespace Microsoft.AspNet.WebUtilities
 
         private Stream CreateTempFile()
         {
+            if (_tempFileDirectory == null)
+            {
+                Debug.Assert(_tempFileDirectoryAccessor != null);
+                _tempFileDirectory = _tempFileDirectoryAccessor();
+                Debug.Assert(_tempFileDirectory != null);
+            }
+
             var fileName = Path.Combine(_tempFileDirectory, "ASPNET_" + Guid.NewGuid().ToString() + ".tmp");
             return new FileStream(fileName, FileMode.Create, FileAccess.ReadWrite, FileShare.Delete, 1024 * 16,
                 FileOptions.Asynchronous | FileOptions.DeleteOnClose | FileOptions.SequentialScan);