diff --git a/django/contrib/auth/forms.py b/django/contrib/auth/forms.py
index e6eb5a736b..07e1e51c17 100644
--- a/django/contrib/auth/forms.py
+++ b/django/contrib/auth/forms.py
@@ -1,4 +1,4 @@
-from django.contrib.auth.models import User
+from django.contrib.auth.models import User, UNUSABLE_PASSWORD
 from django.contrib.auth import authenticate
 from django.contrib.auth.tokens import default_token_generator
 from django.contrib.sites.models import Site
@@ -21,6 +21,11 @@ class UserCreationForm(forms.ModelForm):
         model = User
         fields = ("username",)
 
+    def clean(self):
+        # avoid check for blank=True on the model field
+        self.instance.password = UNUSABLE_PASSWORD
+        super(UserCreationForm, self).clean()
+
     def clean_username(self):
         username = self.cleaned_data["username"]
         try: