diff --git a/sigal/gallery.py b/sigal/gallery.py
index fc3afe7..7563ec8 100644
--- a/sigal/gallery.py
+++ b/sigal/gallery.py
@@ -445,7 +445,8 @@ class Album:
                         size = get_size(f.src_path)
 
                     if size['width'] > size['height']:
-                        self._thumbnail = self.name + '/' + f.thumbnail
+                        self._thumbnail = (url_quote(self.name) + '/' +
+                                           f.thumbnail)
                         self.logger.debug(
                             "Use 1st landscape image as thumbnail for %r : %s",
                             self, self._thumbnail)
@@ -455,7 +456,8 @@ class Album:
             if not self._thumbnail and self.medias:
                 for media in self.medias:
                     if media.thumbnail is not None:
-                        self._thumbnail = self.name + '/' + media.thumbnail
+                        self._thumbnail = (url_quote(self.name) + '/' +
+                                           media.thumbnail)
                         break
                 else:
                     self.logger.warning("No thumbnail found for %r", self)
@@ -469,7 +471,8 @@ class Album:
             if not self._thumbnail:
                 for path, album in self.gallery.get_albums(self.path):
                     if album.thumbnail:
-                        self._thumbnail = self.name + '/' + album.thumbnail
+                        self._thumbnail = (url_quote(self.name) + '/' +
+                                           album.thumbnail)
                         self.logger.debug(
                             "Using thumbnail from sub-directory for %r : %s",
                             self, self._thumbnail)
diff --git a/tests/test_gallery.py b/tests/test_gallery.py
index 2f58cf5..849fa10 100644
--- a/tests/test_gallery.py
+++ b/tests/test_gallery.py
@@ -54,7 +54,7 @@ REF = {
     'accentué': {
         'title': 'accentué',
         'name': 'accentué',
-        'thumbnail': 'accentué/thumbnails/h%C3%A9lico%C3%AFde.tn.jpg',
+        'thumbnail': 'accentu%C3%A9/thumbnails/h%C3%A9lico%C3%AFde.tn.jpg',
         'subdirs': [],
         'medias': ['hélicoïde.jpg', '11.jpg'],
     },