diff --git a/app/models/discourse_single_sign_on.rb b/app/models/discourse_single_sign_on.rb
index 20505879817..aefa944a88f 100644
--- a/app/models/discourse_single_sign_on.rb
+++ b/app/models/discourse_single_sign_on.rb
@@ -108,7 +108,7 @@ class DiscourseSingleSignOn < SingleSignOn
 
   def apply_group_rules(user)
     if add_groups
-      split = add_groups.split(",")
+      split = add_groups.split(",").map(&:downcase)
       if split.length > 0
         Group.where('name in (?) AND NOT automatic', split).pluck(:id).each do |id|
           unless GroupUser.where(group_id: id, user_id: user.id).exists?
diff --git a/spec/models/discourse_single_sign_on_spec.rb b/spec/models/discourse_single_sign_on_spec.rb
index 451b909dbc9..e1aa9aadfbe 100644
--- a/spec/models/discourse_single_sign_on_spec.rb
+++ b/spec/models/discourse_single_sign_on_spec.rb
@@ -141,7 +141,7 @@ describe DiscourseSingleSignOn do
     sso.email = user.email
     sso.external_id = "A"
 
-    sso.add_groups = "#{add_group1.name},#{add_group2.name},badname"
+    sso.add_groups = "#{add_group1.name},#{add_group2.name.capitalize},badname"
     sso.remove_groups = "#{existing_group.name},badname"
 
     sso.lookup_or_create_user(ip_address)