diff --git a/passbook/providers/saml/models.py b/passbook/providers/saml/models.py
index 2e7bd68f4..b98c67fae 100644
--- a/passbook/providers/saml/models.py
+++ b/passbook/providers/saml/models.py
@@ -147,7 +147,10 @@ class SAMLPropertyMapping(PropertyMapping):
     saml_name = models.TextField(verbose_name="SAML Name")
     friendly_name = models.TextField(default=None, blank=True, null=True)
 
-    form = "passbook.providers.saml.forms.SAMLPropertyMappingForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.providers.saml.forms import SAMLPropertyMappingForm
+
+        return SAMLPropertyMappingForm
 
     def __str__(self):
         return f"SAML Property Mapping {self.saml_name}"
diff --git a/passbook/sources/ldap/models.py b/passbook/sources/ldap/models.py
index b4581d11d..4fc1ffc3c 100644
--- a/passbook/sources/ldap/models.py
+++ b/passbook/sources/ldap/models.py
@@ -89,7 +89,10 @@ class LDAPPropertyMapping(PropertyMapping):
 
     object_field = models.TextField()
 
-    form = "passbook.sources.ldap.forms.LDAPPropertyMappingForm"
+    def form(self) -> Type[ModelForm]:
+        from passbook.sources.ldap.forms import LDAPPropertyMappingForm
+
+        return LDAPPropertyMappingForm
 
     def __str__(self):
         return f"LDAP Property Mapping {self.expression} -> {self.object_field}"