diff --git a/e2e/test_provider_oauth.py b/e2e/test_provider_oauth.py
index 6b40bbfc7..8733a15e7 100644
--- a/e2e/test_provider_oauth.py
+++ b/e2e/test_provider_oauth.py
@@ -103,9 +103,9 @@ class TestProviderOAuth(SeleniumTestCase):
             USER().username,
         )
         self.assertEqual(
-            self.driver.find_element(
-                By.CSS_SELECTOR, "input[name=name]"
-            ).get_attribute("value"),
+            self.driver.find_element(By.CSS_SELECTOR, "input[name=name]").get_attribute(
+                "value"
+            ),
             USER().username,
         )
         self.assertEqual(
@@ -172,9 +172,9 @@ class TestProviderOAuth(SeleniumTestCase):
             USER().username,
         )
         self.assertEqual(
-            self.driver.find_element(
-                By.CSS_SELECTOR, "input[name=name]"
-            ).get_attribute("value"),
+            self.driver.find_element(By.CSS_SELECTOR, "input[name=name]").get_attribute(
+                "value"
+            ),
             USER().username,
         )
         self.assertEqual(
diff --git a/e2e/test_provider_oidc.py b/e2e/test_provider_oidc.py
index c9ae3524c..779a048bf 100644
--- a/e2e/test_provider_oidc.py
+++ b/e2e/test_provider_oidc.py
@@ -153,9 +153,9 @@ class TestProviderOIDC(SeleniumTestCase):
             USER().name,
         )
         self.assertEqual(
-            self.driver.find_element(
-                By.CSS_SELECTOR, "input[name=name]"
-            ).get_attribute("value"),
+            self.driver.find_element(By.CSS_SELECTOR, "input[name=name]").get_attribute(
+                "value"
+            ),
             USER().name,
         )
         self.assertEqual(
@@ -232,9 +232,9 @@ class TestProviderOIDC(SeleniumTestCase):
             USER().name,
         )
         self.assertEqual(
-            self.driver.find_element(
-                By.CSS_SELECTOR, "input[name=name]"
-            ).get_attribute("value"),
+            self.driver.find_element(By.CSS_SELECTOR, "input[name=name]").get_attribute(
+                "value"
+            ),
             USER().name,
         )
         self.assertEqual(
diff --git a/passbook/core/models.py b/passbook/core/models.py
index 3febb463a..ad91b616c 100644
--- a/passbook/core/models.py
+++ b/passbook/core/models.py
@@ -1,12 +1,13 @@
 """passbook core models"""
 from datetime import timedelta
-from typing import Any, Optional
+from typing import Any, Optional, Type
 from uuid import uuid4
 
 from django.contrib.auth.models import AbstractUser
 from django.contrib.postgres.fields import JSONField
 from django.db import models
 from django.db.models import Q, QuerySet
+from django.forms import ModelForm
 from django.http import HttpRequest
 from django.utils.timezone import now
 from django.utils.translation import gettext_lazy as _
@@ -162,10 +163,12 @@ class Source(PolicyBindingModel):
         related_name="source_enrollment",
     )
 
-    form = ""  # ModelForm-based class ued to create/edit instance
-
     objects = InheritanceManager()
 
+    def form(self) -> Type[ModelForm]:
+        """Return Form class used to edit this object"""
+        raise NotImplementedError
+
     @property
     def ui_login_button(self) -> Optional[UILoginButton]:
         """If source uses a http-based flow, return UI Information about the login
@@ -261,9 +264,12 @@ class PropertyMapping(models.Model):
     name = models.TextField()
     expression = models.TextField()
 
-    form = ""
     objects = InheritanceManager()
 
+    def form(self) -> Type[ModelForm]:
+        """Return Form class used to edit this object"""
+        raise NotImplementedError
+
     def evaluate(
         self, user: Optional[User], request: Optional[HttpRequest], **kwargs
     ) -> Any:
diff --git a/passbook/sources/ldap/models.py b/passbook/sources/ldap/models.py
index 0de975870..b4581d11d 100644
--- a/passbook/sources/ldap/models.py
+++ b/passbook/sources/ldap/models.py
@@ -1,8 +1,9 @@
 """passbook LDAP Models"""
-from typing import Optional
+from typing import Optional, Type
 
 from django.core.validators import URLValidator
 from django.db import models
+from django.forms import ModelForm
 from django.utils.translation import gettext_lazy as _
 from ldap3 import Connection, Server
 
@@ -53,7 +54,10 @@ class LDAPSource(Source):
         Group, blank=True, null=True, default=None, on_delete=models.SET_DEFAULT
     )
 
-    form = "passbook.sources.ldap.forms.LDAPSourceForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.sources.ldap.forms import LDAPSourceForm
+
+        return LDAPSourceForm
 
     _connection: Optional[Connection] = None
 
diff --git a/passbook/sources/oauth/models.py b/passbook/sources/oauth/models.py
index 95262f32f..ff97d84f2 100644
--- a/passbook/sources/oauth/models.py
+++ b/passbook/sources/oauth/models.py
@@ -1,7 +1,8 @@
 """OAuth Client models"""
-from typing import Optional
+from typing import Optional, Type
 
 from django.db import models
+from django.forms import ModelForm
 from django.urls import reverse, reverse_lazy
 from django.utils.translation import gettext_lazy as _
 
@@ -40,7 +41,10 @@ class OAuthSource(Source):
     consumer_key = models.TextField()
     consumer_secret = models.TextField()
 
-    form = "passbook.sources.oauth.forms.OAuthSourceForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.sources.oauth.forms import OAuthSourceForm
+
+        return OAuthSourceForm
 
     @property
     def ui_login_button(self) -> UILoginButton:
@@ -80,7 +84,10 @@ class OAuthSource(Source):
 class GitHubOAuthSource(OAuthSource):
     """Social Login using GitHub.com or a GitHub-Enterprise Instance."""
 
-    form = "passbook.sources.oauth.forms.GitHubOAuthSourceForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.sources.oauth.forms import GitHubOAuthSourceForm
+
+        return GitHubOAuthSourceForm
 
     class Meta:
 
@@ -92,7 +99,9 @@ class GitHubOAuthSource(OAuthSource):
 # class TwitterOAuthSource(OAuthSource):
 #     """Social Login using Twitter.com"""
 
-#     form = "passbook.sources.oauth.forms.TwitterOAuthSourceForm"
+#     def form(self) -> Type[ModelForm]:
+#         from passbook.sources.oauth.forms import TwitterOAuthSourceForm
+#         return TwitterOAuthSourceForm
 
 #     class Meta:
 
@@ -104,7 +113,10 @@ class GitHubOAuthSource(OAuthSource):
 class FacebookOAuthSource(OAuthSource):
     """Social Login using Facebook.com."""
 
-    form = "passbook.sources.oauth.forms.FacebookOAuthSourceForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.sources.oauth.forms import FacebookOAuthSourceForm
+
+        return FacebookOAuthSourceForm
 
     class Meta:
 
@@ -116,7 +128,10 @@ class FacebookOAuthSource(OAuthSource):
 class DiscordOAuthSource(OAuthSource):
     """Social Login using Discord."""
 
-    form = "passbook.sources.oauth.forms.DiscordOAuthSourceForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.sources.oauth.forms import DiscordOAuthSourceForm
+
+        return DiscordOAuthSourceForm
 
     class Meta:
 
@@ -128,7 +143,10 @@ class DiscordOAuthSource(OAuthSource):
 class GoogleOAuthSource(OAuthSource):
     """Social Login using Google or Gsuite."""
 
-    form = "passbook.sources.oauth.forms.GoogleOAuthSourceForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.sources.oauth.forms import GoogleOAuthSourceForm
+
+        return GoogleOAuthSourceForm
 
     class Meta:
 
@@ -140,7 +158,10 @@ class GoogleOAuthSource(OAuthSource):
 class AzureADOAuthSource(OAuthSource):
     """Social Login using Azure AD."""
 
-    form = "passbook.sources.oauth.forms.AzureADOAuthSourceForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.sources.oauth.forms import AzureADOAuthSourceForm
+
+        return AzureADOAuthSourceForm
 
     class Meta:
 
@@ -152,7 +173,10 @@ class AzureADOAuthSource(OAuthSource):
 class OpenIDOAuthSource(OAuthSource):
     """Login using a Generic OpenID-Connect compliant provider."""
 
-    form = "passbook.sources.oauth.forms.OAuthSourceForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.sources.oauth.forms import OAuthSourceForm
+
+        return OAuthSourceForm
 
     class Meta:
 
diff --git a/passbook/sources/saml/models.py b/passbook/sources/saml/models.py
index 33e1b3da9..9a76a83d8 100644
--- a/passbook/sources/saml/models.py
+++ b/passbook/sources/saml/models.py
@@ -1,5 +1,8 @@
 """saml sp models"""
+from typing import Type
+
 from django.db import models
+from django.forms import ModelForm
 from django.http import HttpRequest
 from django.shortcuts import reverse
 from django.urls import reverse_lazy
@@ -93,7 +96,10 @@ class SAMLSource(Source):
         on_delete=models.PROTECT,
     )
 
-    form = "passbook.sources.saml.forms.SAMLSourceForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.sources.saml.forms import SAMLSourceForm
+
+        return SAMLSourceForm
 
     def get_issuer(self, request: HttpRequest) -> str:
         """Get Source's Issuer, falling back to our Metadata URL if none is set"""