diff --git a/src/migration/migrationTemplate.txt b/src/migration/migrationTemplate.txt
index 53b4e35..7656e2f 100644
--- a/src/migration/migrationTemplate.txt
+++ b/src/migration/migrationTemplate.txt
@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"git.handmade.network/hmn/hmn/src/migration/types"
+	"git.handmade.network/hmn/hmn/src/oops"
 	"github.com/jackc/pgx/v4"
 )
 
diff --git a/src/migration/migrations/2021-04-27T034327Z_UsernameUniqueIndex.go b/src/migration/migrations/2021-04-27T034327Z_UsernameUniqueIndex.go
new file mode 100644
index 0000000..e54b8a6
--- /dev/null
+++ b/src/migration/migrations/2021-04-27T034327Z_UsernameUniqueIndex.go
@@ -0,0 +1,40 @@
+package migrations
+
+import (
+	"context"
+	"time"
+
+	"git.handmade.network/hmn/hmn/src/migration/types"
+	"git.handmade.network/hmn/hmn/src/oops"
+	"github.com/jackc/pgx/v4"
+)
+
+func init() {
+	registerMigration(UsernameUniqueIndex{})
+}
+
+type UsernameUniqueIndex struct{}
+
+func (m UsernameUniqueIndex) Version() types.MigrationVersion {
+	return types.MigrationVersion(time.Date(2021, 4, 27, 3, 43, 27, 0, time.UTC))
+}
+
+func (m UsernameUniqueIndex) Name() string {
+	return "UsernameUniqueIndex"
+}
+
+func (m UsernameUniqueIndex) Description() string {
+	return "Prevent the creation of similar usernames with different character cases"
+}
+
+func (m UsernameUniqueIndex) Up(ctx context.Context, tx pgx.Tx) error {
+	_, err := tx.Exec(ctx, `CREATE UNIQUE INDEX auth_user_unique_username_case_insensitive ON auth_user (LOWER(username))`)
+	if err != nil {
+		return oops.New(err, "failed to add unique index")
+	}
+	return nil
+}
+
+func (m UsernameUniqueIndex) Down(ctx context.Context, tx pgx.Tx) error {
+	panic("Implement me")
+}
diff --git a/src/website/login.go b/src/website/login.go
index f0a7b18..bc7e7b2 100644
--- a/src/website/login.go
+++ b/src/website/login.go
@@ -30,7 +30,7 @@ func Login(c *RequestContext) ResponseData {
 		redirect = "/"
 	}
 
-	userRow, err := db.QueryOne(c.Context(), c.Conn, models.User{}, "SELECT $columns FROM auth_user WHERE username = $1", username)
+	userRow, err := db.QueryOne(c.Context(), c.Conn, models.User{}, "SELECT $columns FROM auth_user WHERE LOWER(username) = LOWER($1)", username)
 	if err != nil {
 		if errors.Is(err, db.ErrNoMatchingRows) {
 			return ResponseData{
@@ -57,7 +57,7 @@ func Login(c *RequestContext) ResponseData {
 		if hashed.IsOutdated() {
 			newHashed, err := auth.HashPassword(password)
 			if err == nil {
-				err := auth.UpdatePassword(c.Context(), c.Conn, username, newHashed)
+				err := auth.UpdatePassword(c.Context(), c.Conn, user.Username, newHashed)
 				if err != nil {
 					c.Logger.Error().Err(err).Msg("failed to update user's password")
 				}
@@ -67,7 +67,7 @@ func Login(c *RequestContext) ResponseData {
 			// If errors happen here, we can still continue with logging them in
 		}
 
-		session, err := auth.CreateSession(c.Context(), c.Conn, username)
+		session, err := auth.CreateSession(c.Context(), c.Conn, user.Username)
 		if err != nil {
 			return ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to create session"))
 		}