diff --git a/modoboa/lib/formutils.py b/modoboa/lib/formutils.py
index 1b05abe0f..f206cd0ec 100644
--- a/modoboa/lib/formutils.py
+++ b/modoboa/lib/formutils.py
@@ -210,7 +210,7 @@ class CustomRadioInput(RadioInput):
             label_for = ''
         choice_label = conditional_escape(force_unicode(self.choice_label))
         return mark_safe(
-            u'<label class="radio inline" %s>%s %s</label>'
+            u'<label class="radio-inline" %s>%s %s</label>'
             % (label_for, self.tag(), choice_label)
         )