diff --git a/db.sql b/db.sql
index 840a595..b4025e6 100644
--- a/db.sql
+++ b/db.sql
@@ -2,6 +2,7 @@ DROP TABLE IF EXISTS books;
 
 CREATE TABLE books (
     id SERIAL PRIMARY KEY,
-    title VARCHAR(50) UNIQUE NOT NULL,
-    author VARCHAR(100) UNIQUE NOT NULL
+    title VARCHAR(255) NOT NULL,
+    author VARCHAR(255) NOT NULL,
+    publisher VARCHAR(255)
 );
diff --git a/models.py b/models.py
index bd73c60..6546b85 100644
--- a/models.py
+++ b/models.py
@@ -1,6 +1,7 @@
 from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
 from sqlalchemy import String
 from pydantic import BaseModel, ConfigDict
+from typing import Optional
 
 
 # SQLAlchemy models
@@ -18,6 +19,7 @@ class Book(Base):
     id: Mapped[int] = mapped_column(primary_key=True, index=True)
     title: Mapped[str] = mapped_column(String(255), index=True)
     author: Mapped[str] = mapped_column(String(255))
+    publisher: Mapped[Optional[str]] = mapped_column(String(255), nullable=True)
 
 # Pydantic models
 class BookIn(BaseModel):
@@ -25,6 +27,7 @@ class BookIn(BaseModel):
 
     title: str
     author: str
+    publisher: Optional[str] = None
 
 
 class BookOut(BaseModel):
@@ -33,5 +36,6 @@ class BookOut(BaseModel):
     id: int
     title: str
     author: str
+    publisher: Optional[str] = None
 
     model_config = ConfigDict(from_attributes=True)
diff --git a/repositories.py b/repositories.py
index dc9ff88..6c4642b 100644
--- a/repositories.py
+++ b/repositories.py
@@ -4,7 +4,11 @@
 
 # Create a new book
 def create_book(db: Session, book: models.BookIn):
-    db_book = models.Book(title=book.title, author=book.author)
+    db_book = models.Book(
+        title=book.title,
+        author=book.author,
+        publisher=book.publisher
+    )
     db.add(db_book)
     db.commit()
     db.refresh(db_book)
@@ -27,6 +31,7 @@ def update_book(db: Session, book_id: int, book: models.BookIn):
     if db_book:
         db_book.title = book.title
         db_book.author = book.author
+        db_book.publisher = book.publisher
         db.commit()
         db.refresh(db_book)
         return db_book