diff --git a/registration/forms.py b/registration/forms.py
index 79e893c3..320b4ac4 100644
--- a/registration/forms.py
+++ b/registration/forms.py
@@ -9,6 +9,9 @@ class RegistrationForm(forms.Form):
     email_again = forms.CharField(max_length=254, required=True, label="Email Again")
 
     def clean(self):
+        if ' ' in self.cleaned_data['username']:
+            raise forms.ValidationError(u'Username can not contain a space')
+        
         if 'password' in self.cleaned_data and 'password_again' in self.cleaned_data:
             if self.cleaned_data['password'] != self.cleaned_data['password_again']:
                 raise forms.ValidationError(u'Passwords do not match')