diff --git a/ebook/__init__.py b/ebook/__init__.py
index e064d1b..3b7bb0e 100644
--- a/ebook/__init__.py
+++ b/ebook/__init__.py
@@ -156,7 +156,7 @@ def chapter_html(
     return chapters
 
 
-def generate_epub(story, cover_options={}, image_options=None,  output_filename=None, output_dir=None, normalize=False):
+def generate_epub(story, cover_options={}, image_options=None,  output_filename=None, output_dir=None, normalize=False, allow_spaces=False):
     if image_options is None:
         image_options = {
             'image_fetch': False,
@@ -225,5 +225,6 @@ def generate_epub(story, cover_options={}, image_options=None,  output_filename=
                      contents=image.read(), filetype='image/png'),
         ],
         metadata,
-        output_dir=output_dir
+        output_dir=output_dir,
+        allow_spaces=allow_spaces
     )
diff --git a/ebook/epub.py b/ebook/epub.py
index 7a1bfcb..4315977 100644
--- a/ebook/epub.py
+++ b/ebook/epub.py
@@ -18,7 +18,7 @@
 EpubFile = namedtuple('EbookFile', 'path, contents, title, filetype', defaults=(False, False, "application/xhtml+xml"))
 
 
-def sanitize_filename(s):
+def sanitize_filename(s, allow_spaces=False):
     """Take a string and return a valid filename constructed from the string.
     Uses a whitelist approach: any characters not present in valid_chars are
     removed. Also spaces are replaced with underscores.
@@ -31,16 +31,17 @@ def sanitize_filename(s):
     """
     valid_chars = "-_.() %s%s" % (string.ascii_letters, string.digits)
     filename = ''.join(c for c in s if c in valid_chars)
-    filename = filename.replace(' ', '_')  # I don't like spaces in filenames.
+    if not allow_spaces:
+        filename = filename.replace(' ', '_')  # I don't like spaces in filenames.
     return filename
 
 
-def make_epub(filename, files, meta, compress=True, output_dir=False):
+def make_epub(filename, files, meta, compress=True, output_dir=False, allow_spaces=False):
     unique_id = meta.get('unique_id', False)
     if not unique_id:
         unique_id = 'leech_book_' + str(uuid.uuid4())
 
-    filename = sanitize_filename(filename)
+    filename = sanitize_filename(filename, allow_spaces)
     if output_dir:
         filename = os.path.join(output_dir, filename)
     epub = zipfile.ZipFile(filename, 'w', compression=compress and zipfile.ZIP_DEFLATED or zipfile.ZIP_STORED)
diff --git a/leech.py b/leech.py
index 3bb728a..3b11abf 100755
--- a/leech.py
+++ b/leech.py
@@ -180,7 +180,8 @@ def download(urls, site_options, cache, verbose, normalize, output_dir, **other_
                     'always_convert_images': options.get('always_convert_images', False)
                 },
                 normalize=normalize,
-                output_dir=output_dir or options.get('output_dir', os.getcwd())
+                output_dir=output_dir or options.get('output_dir', os.getcwd()),
+                allow_spaces=options.get('allow_spaces', False)
             )
             logger.info("File created: " + filename)
         else: