diff --git a/lib/clearance/user.rb b/lib/clearance/user.rb
index a4369d474..6eb7d71e8 100644
--- a/lib/clearance/user.rb
+++ b/lib/clearance/user.rb
@@ -152,7 +152,7 @@ module Validations
         validates :email,
           email: { strict_mode: true },
           presence: true,
-          uniqueness: { allow_blank: true, case_sensitive: false },
+          uniqueness: { allow_blank: true, case_sensitive: true },
           unless: :email_optional?
 
         validates :password, presence: true, unless: :skip_password_validation?