diff --git a/pelican/settings.py b/pelican/settings.py
index a4033001..a5cbc69f 100644
--- a/pelican/settings.py
+++ b/pelican/settings.py
@@ -144,7 +144,9 @@ DEFAULT_CONFIG = {
     'TEMPLATE_EXTENSIONS': ['.html'],
     'IGNORE_FILES': ['.#*'],
     'SLUG_REGEX_SUBSTITUTIONS': [
-        (r'[^\w\s-]', ''),  # remove non-alphabetical/whitespace/'-' chars
+        # remove all characters except alphanumeric, whitespace,
+        # '_', '-', '+', '#' characters
+        (r'[^\w\s\-#\+]', ''),
         (r'(?u)\A\s*', ''),  # strip leading whitespace
         (r'(?u)\s*\Z', ''),  # strip trailing whitespace
         (r'[-\s]+', '-'),  # reduce multiple whitespace or '-' to single '-'
@@ -387,7 +389,7 @@ def handle_deprecated_settings(settings):
 
                 if replace:
                     regex_subs += [
-                        (r'[^\w\s-]', ''),
+                        (r'[^\w\s\-#\+]', ''),
                         (r'(?u)\A\s*', ''),
                         (r'(?u)\s*\Z', ''),
                         (r'[-\s]+', '-'),
diff --git a/pelican/tests/test_utils.py b/pelican/tests/test_utils.py
index ad90a78e..53346508 100644
--- a/pelican/tests/test_utils.py
+++ b/pelican/tests/test_utils.py
@@ -125,7 +125,7 @@ class TestUtils(LoggedTestCase):
     def test_slugify_substitute(self):
 
         samples = (('C++ is based on C', 'cpp-is-based-on-c'),
-                   ('C+++ test C+ test', 'cpp-test-c-test'),
+                   ('C+++ test C+ test', 'cpp+-test-c+-test'),
                    ('c++, c#, C#, C++', 'cpp-c-sharp-c-sharp-cpp'),
                    ('c++-streams', 'cpp-streams'),)