diff --git a/weboob/backends/mediawiki/backend.py b/weboob/backends/mediawiki/backend.py
index cee49e94..5a011b7d 100644
--- a/weboob/backends/mediawiki/backend.py
+++ b/weboob/backends/mediawiki/backend.py
@@ -36,8 +36,8 @@ class MediawikiBackend(BaseBackend, ICapContent):
     VERSION = '0.a'
     LICENSE = 'AGPLv3+'
     DESCRIPTION = 'Mediawiki wiki software application'
-    CONFIG = BackendConfig(Value('url',      label='URL of the Mediawiki website', default='http://en.wikipedia.org/'),
-                           Value('apiurl',   label='URL of the Mediawiki website\'s API', default='http://en.wikipedia.org/w/api.php'),
+    CONFIG = BackendConfig(Value('url',      label='URL of the Mediawiki website', default='http://en.wikipedia.org/', regexp='https?://.*'),
+                           Value('apiurl',   label='URL of the Mediawiki website\'s API', default='http://en.wikipedia.org/w/api.php', regexp='https?://.*'),
                            Value('username', label='Login', default=''),
                            ValueBackendPassword('password', label='Password', default=''))
 
diff --git a/weboob/backends/newsfeed/backend.py b/weboob/backends/newsfeed/backend.py
index 984005e6..5b7a246c 100644
--- a/weboob/backends/newsfeed/backend.py
+++ b/weboob/backends/newsfeed/backend.py
@@ -34,7 +34,7 @@ class NewsfeedBackend(BaseBackend, ICapMessages):
     VERSION = '0.a'
     DESCRIPTION = "Loads RSS and Atom feeds from any website"
     LICENSE = "AGPLv3+"
-    CONFIG = BackendConfig(Value('url', label="Atom/RSS feed's url"))
+    CONFIG = BackendConfig(Value('url', label="Atom/RSS feed's url", regexp='https?://.*'))
     STORAGE = {'seen': []}
 
 
diff --git a/weboob/backends/redmine/backend.py b/weboob/backends/redmine/backend.py
index b32752b9..7482875f 100644
--- a/weboob/backends/redmine/backend.py
+++ b/weboob/backends/redmine/backend.py
@@ -42,7 +42,7 @@ class RedmineBackend(BaseBackend, ICapContent, ICapBugTracker, ICapCollection):
     VERSION = '0.a'
     DESCRIPTION = 'The Redmine project management web application'
     LICENSE = 'AGPLv3+'
-    CONFIG = BackendConfig(Value('url',      label='URL of the Redmine website'),
+    CONFIG = BackendConfig(Value('url',      label='URL of the Redmine website', regexp=r'https?://.*'),
                            Value('username', label='Login'),
                            ValueBackendPassword('password', label='Password'))
     BROWSER = RedmineBrowser