diff --git a/src/main/java/com/mirna/hospitalmanagementapi/domain/entities/auth/User.java b/src/main/java/com/mirna/hospitalmanagementapi/domain/entities/auth/User.java
index b05ccd7..935bedf 100644
--- a/src/main/java/com/mirna/hospitalmanagementapi/domain/entities/auth/User.java
+++ b/src/main/java/com/mirna/hospitalmanagementapi/domain/entities/auth/User.java
@@ -43,7 +43,7 @@ public class User implements UserDetails {
 	private Long id;
 
 	@NotBlank(message = "login cannot be blank")
-	@Column(name = "login")
+	@Column(name = "login", unique=true)
 	private String login;
 
 	@NotBlank(message = "password cannot be blank")
@@ -62,7 +62,7 @@ public class User implements UserDetails {
 	/**
 	 * Sets the user id.
 	 * 
-	 * @param id The user's unique identifier.
+	 * @param id The user's unique identifier. Must be unique.
 	 */
 	public void setId(Long id) {
 		this.id = id;
diff --git a/src/main/resources/db/migration/V6__slter-table-modify-column-users.sql b/src/main/resources/db/migration/V6__slter-table-modify-column-users.sql
new file mode 100644
index 0000000..b808995
--- /dev/null
+++ b/src/main/resources/db/migration/V6__slter-table-modify-column-users.sql
@@ -0,0 +1,2 @@
+ALTER TABLE users
+MODIFY COLUMN login varchar(250) not null unique;