diff --git a/src/core/entityint.cpp b/src/core/entityint.cpp
index ba8c356..835c5ff 100644
--- a/src/core/entityint.cpp
+++ b/src/core/entityint.cpp
@@ -1,5 +1,9 @@
 #include "entityint.h"
 
+EntityInt::EntityInt(int id) {
+    id_ = id;
+}
+
 void EntityInt::setId(int id) {
     id_ = id;
 }
diff --git a/src/core/entityint.h b/src/core/entityint.h
index 1a1cf59..9430a70 100644
--- a/src/core/entityint.h
+++ b/src/core/entityint.h
@@ -5,11 +5,13 @@
 
 class EntityInt : public Entity
 {
-public:
+  public:
+    EntityInt() = default;
+    EntityInt(int id);
     void setId(int id);
-    int getId() const {return id_;};
-    
-protected:
+    int getId() const { return id_; };
+
+  protected:
     int id_{};
 };
 
diff --git a/src/core/seller.cpp b/src/core/seller.cpp
index bcb470d..cc053ce 100644
--- a/src/core/seller.cpp
+++ b/src/core/seller.cpp
@@ -7,15 +7,14 @@
 
 Seller::Seller(const std::string& firstName, const std::string& lastName, int sellerNo,
                int numArticlesOffered)
-    : EntityInt()
+    : EntityInt(sellerNo)
 {
     firstName_ = firstName;
     lastName_ = lastName;
-    sellerNo_ = sellerNo;
     numArticlesOffered_ = numArticlesOffered;
 }
 
-void Seller::setSellerNo(int seller_no) { sellerNo_ = seller_no; id_ = seller_no;}
+void Seller::setSellerNo(int seller_no) { setId(seller_no); }
 
 void Seller::setFirstName(const std::string& firstName) { firstName_ = firstName; }
 
@@ -33,13 +32,13 @@ std::string Seller::getFirstName() const { return firstName_; }
 
 std::string Seller::getLastName() const { return lastName_; }
 
-int Seller::getSellerNo() const { return sellerNo_; }
+int Seller::getSellerNo() const { return getId(); }
 
 std::string Seller::getSellerNoAsString() const
 {
     std::stringstream selNoStr;
 
-    selNoStr << std::setfill('0') << std::setw(3) << sellerNo_;
+    selNoStr << std::setfill('0') << std::setw(3) << id_;
 
     return selNoStr.str();
     ;
@@ -104,8 +103,8 @@ int Seller::sumInCents()
 
 std::string Seller::sumAsString() { return formatCentAsEuroString(sumInCents()); }
 
-bool operator<(const Seller& li, const Seller& re) { return li.sellerNo_ < re.sellerNo_; }
+bool operator<(const Seller& li, const Seller& re) { return li.id_ < re.id_; }
 bool operator<(const std::unique_ptr<Seller>& li, const std::unique_ptr<Seller>& re)
 {
-    return li->sellerNo_ < re->sellerNo_;
+    return li->id_ < re->id_;
 }
diff --git a/src/core/seller.h b/src/core/seller.h
index bcfa50f..a4bfde1 100644
--- a/src/core/seller.h
+++ b/src/core/seller.h
@@ -14,7 +14,7 @@ class Seller : public EntityInt
 {
   public:
     Seller() = default;
-    // virtual ~Seller() = default;
+    ~Seller() = default;
     Seller(const std::string& firstName, const std::string& lastName, int sellerNo = 0,
            int numArticlesOffered = 0);
 
@@ -42,7 +42,6 @@ class Seller : public EntityInt
     friend bool operator<(const std::unique_ptr<Seller>& li, const std::unique_ptr<Seller>& re);
 
   private:
-    int sellerNo_{-1};
     int numArticlesOffered_{};
     std::string firstName_{};
     std::string lastName_{};