diff --git a/app/models/client.rb b/app/models/client.rb
index 49df689..8dde180 100644
--- a/app/models/client.rb
+++ b/app/models/client.rb
@@ -3,7 +3,8 @@ class Client < ApplicationRecord
   has_many :owner_subprojects, class_name: 'Subproject', foreign_key: 'owner_id'
   has_many :builder_subprojects, class_name: 'Subproject', foreign_key: 'builder_id'
 
-  validates :company_name, :firstname, :lastname, :email, presence: true
+  validates :company_name, :firstname, :lastname, presence: true
+  validates :email, presence: true, uniqueness: true
 
   def referenced_count
     owner_subprojects.count + builder_subprojects.count + client_subprojects.count