diff --git a/bookstore/src/main/java/com/fjordtek/bookstore/model/Book.java b/bookstore/src/main/java/com/fjordtek/bookstore/model/Book.java
index d3b2537..8ab78c0 100644
--- a/bookstore/src/main/java/com/fjordtek/bookstore/model/Book.java
+++ b/bookstore/src/main/java/com/fjordtek/bookstore/model/Book.java
@@ -73,7 +73,7 @@ public class Book {
 			name         = "bookIdGenerator",
 			sequenceName = "bookIdSequence"
 			)
-    private long id;
+    private Long id;
 
 	////////////////////
 	// Attributes with hard-coded constraints
@@ -170,7 +170,7 @@ public class Book {
 	// TODO consider accessibility restrictions?
 
 	// NOTE: in default scenario, this is automatically generated
-	public void setId(long id) {
+	public void setId(Long id) {
 		this.id = id;
 	}
 
@@ -203,7 +203,7 @@ public class Book {
 
 	// TODO consider accessibility restrictions?
 
-	public long getId() {
+	public Long getId() {
 		return id;
 	}
 
diff --git a/bookstore/src/main/java/com/fjordtek/bookstore/model/Category.java b/bookstore/src/main/java/com/fjordtek/bookstore/model/Category.java
index fe3aa53..64df084 100644
--- a/bookstore/src/main/java/com/fjordtek/bookstore/model/Category.java
+++ b/bookstore/src/main/java/com/fjordtek/bookstore/model/Category.java
@@ -25,7 +25,7 @@ public class Category {
 			name         = "categoryIdGenerator",
 			sequenceName = "categoryIdSequence"
 			)
-    private long id;
+    private Long id;
 
 	////////////////////
 	// Attributes with hard-coded constraints
@@ -41,7 +41,7 @@ public class Category {
 	////////////////////
 	// Attribute setters
 
-	public void setId(long id) {
+	public void setId(Long id) {
 		this.id = id;
 	}
 
@@ -56,7 +56,7 @@ public class Category {
 	////////////////////
 	// Attribute getters
 
-	public long getId() {
+	public Long getId() {
 		return id;
 	}
 
diff --git a/bookstore/src/main/java/com/fjordtek/bookstore/web/BookController.java b/bookstore/src/main/java/com/fjordtek/bookstore/web/BookController.java
index 67d0ddf..9222f27 100644
--- a/bookstore/src/main/java/com/fjordtek/bookstore/web/BookController.java
+++ b/bookstore/src/main/java/com/fjordtek/bookstore/web/BookController.java
@@ -124,7 +124,7 @@ public class BookController {
 			method = RequestMethod.GET
 			)
 	public String webFormDeleteBook(
-			@PathVariable("id") long bookId,
+			@PathVariable("id") Long bookId,
 			HttpServletRequest requestData
 			) {
 
@@ -146,7 +146,7 @@ public class BookController {
 			method = { RequestMethod.GET }
 			)
 	public String webFormEditBook(
-			@PathVariable("id") long bookId,
+			@PathVariable("id") Long bookId,
 			Model dataModel,
 			HttpServletRequest requestData
 			) {
@@ -177,7 +177,7 @@ public class BookController {
 	public String webFormUpdateBook(
 			@Valid @ModelAttribute("book") Book book,
 			BindingResult bindingResult,
-			@PathVariable("id") long bookId,
+			@PathVariable("id") Long bookId,
 			HttpServletRequest requestData
 			) {