diff --git a/bookwyrm/forms/custom_form.py b/bookwyrm/forms/custom_form.py
index c604deea4..4a678182b 100644
--- a/bookwyrm/forms/custom_form.py
+++ b/bookwyrm/forms/custom_form.py
@@ -1,5 +1,6 @@
 """ Overrides django's default form class """
 from collections import defaultdict
+from django.core.exceptions import ValidationError
 from django.forms import ModelForm
 from django.forms.widgets import Textarea
 
@@ -34,3 +35,43 @@ class CustomForm(StyledForm):
         """Save and check perms"""
         self.instance.raise_not_editable(request.user)
         return super().save(*args, **kwargs)
+    
+    # def clean(self):
+    #     self.cleaned_data = super().clean()
+
+    #     print("Clean")
+    #     print(self.errors)
+
+    #     for name, field in self.fields.items():
+    #         if self.has_error(field):
+    #             print(field.widget.__dir__())
+    #             self.add_to_attributes(field, "class", "is-danger")
+
+    #     return self.cleaned_data 
+                
+    def add_error(self, field, error):
+        super().add_error(field, error)
+
+        # TODO this (finding the field) is much too complicated; probably this is not the right location?
+        #   it is however more or less what super().add_error does...
+        if (field is None):
+            if isinstance(error, dict):
+                for field_name, messages in error.items():
+                    if field_name in self.fields:
+                        self.add_to_attributes(self.fields[field_name], "class", "is-danger")
+            elif isinstance(error, ValidationError):
+                if hasattr(error, 'error_dict'):
+                    error = error.error_dict
+                    for field_name, error_list in error.items():
+                        if field_name in self.fields:
+                            self.add_to_attributes(self.fields[field_name], "class", "is-danger")
+        else:      
+            self.add_to_attributes(field, "class", "is-danger")
+    
+    # TODO this method looks much too complicated for a simple "field.add_class(class)"?
+    def add_to_attributes(self, field, attr_name, value):
+        current_attributes = field.widget.attrs
+        current_classes = set(current_attributes.get(attr_name, "").split())
+        current_classes.add(value)
+
+        current_attributes[attr_name] = " ".join(current_classes)