diff --git a/api/files.py b/api/files.py
index 1b7abc4f4..d781f86ce 100644
--- a/api/files.py
+++ b/api/files.py
@@ -3,9 +3,10 @@
 import json
 import six
 import hashlib
+import uuid
 
 import fs.move
-import fs.tempfs
+import fs.subfs
 import fs.path
 import fs.errors
 
@@ -16,7 +17,8 @@
 class FileProcessor(object):
     def __init__(self, base, presistent_fs):
         self.base = base
-        self._temp_fs = fs.tempfs.TempFS(identifier='.temp', temp_dir=self.base)
+        self._tempdir_name = str(uuid.uuid4())
+        self._temp_fs = fs.subfs.SubFS(presistent_fs, fs.path.join('tmp', self._tempdir_name))
         self._presistent_fs = presistent_fs
 
     def store_temp_file(self, src_path, dest_path):
@@ -26,7 +28,7 @@ def store_temp_file(self, src_path, dest_path):
             dest_path = six.u(dest_path)
         dst_dir = fs.path.dirname(dest_path)
         self._presistent_fs.makedirs(dst_dir, recreate=True)
-        fs.move.move_file(src_fs=self.temp_fs, src_path=src_path, dst_fs=self._presistent_fs, dst_path=dest_path)
+        self._presistent_fs.move(src_path=fs.path.join('tmp', self._tempdir_name, src_path), dst_path=dest_path)
 
     def process_form(self, request):
         """
@@ -97,7 +99,9 @@ def __del__(self):
         self.close()
 
     def close(self):
-        self.temp_fs.close()
+        # Cleaning up
+        self._presistent_fs.listdir(fs.path.join('tmp', self._tempdir_name))
+        self._presistent_fs.removetree(fs.path.join('tmp', self._tempdir_name))
 
 
 def get_single_file_field_storage(file_system):
@@ -118,6 +122,7 @@ def make_file(self, binary=None):
             # Sanitize form's filename (read: prevent malicious escapes, bad characters, etc)
 
             self.filename = fs.path.basename(self.filename)
+            self.hasher = hashlib.new(DEFAULT_HASH_ALG)
             if not isinstance(self.filename, unicode):
                 self.filename = six.u(self.filename)
             self.open_file = file_system.open(self.filename, 'wb')
@@ -131,10 +136,13 @@ def _FieldStorage__write(self, line):
                 # Always write fields of type "file" to disk for consistent renaming behavior
                 if self.filename:
                     self.file = self.make_file('')
-
                     self.file.write(self._FieldStorage__file.getvalue())
+                    self.hasher.update(self._FieldStorage__file.getvalue())
                 self._FieldStorage__file = None
+
             self.file.write(line)
+            if hasattr(self, 'hasher'):
+                self.hasher.update(line)
 
     return SingleFileFieldStorage
 
diff --git a/api/upload.py b/api/upload.py
index d0a3bd6ff..90c753141 100644
--- a/api/upload.py
+++ b/api/upload.py
@@ -100,6 +100,7 @@ def process_upload(request, strategy, container_type=None, id_=None, origin=None
         raise FileFormException("Targeted uploads can only send one file")
 
     for field in file_fields:
+        field.file.close()
         # Augment the cgi.FieldStorage with a variety of custom fields.
         # Not the best practice. Open to improvements.
         # These are presumbed to be required by every function later called with field as a parameter.
@@ -111,7 +112,7 @@ def process_upload(request, strategy, container_type=None, id_=None, origin=None
                 file_processor.temp_fs.listdir('/'),
             ))
         field.size = file_processor.temp_fs.getsize(field.path)
-        field.hash = file_processor.hash_file_formatted(field.path, file_processor.temp_fs)
+        field.hash = util.format_hash(files.DEFAULT_HASH_ALG, field.hasher.hexdigest())
         field.uuid = str(uuid.uuid4())
         field.mimetype = util.guess_mimetype(field.filename)  # TODO: does not honor metadata's mime type if any
         field.modified = timestamp