diff --git a/state/models.go b/state/models.go
index 035ce4e..0e2b347 100644
--- a/state/models.go
+++ b/state/models.go
@@ -24,7 +24,7 @@ type Namespace struct {
 type Repo struct {
 	BaseModel   `xorm:"extends"`
 	NamespaceID int64  `xorm:"notnull unique(cred)" json:"namespace_id"`
-	Name        string `xorm:"varchar(255) notnull" json:"reponame"`
+	Name        string `xorm:"varchar(255) notnull unique(cred)" json:"reponame"`
 	IsPrivate   bool   `xorm:"default false" json:"is_private"`
 }
 
@@ -111,5 +111,15 @@ func migrateLegacySQLite(engine *xorm.Engine) error {
 			return fmt.Errorf("migrate repo column repo_name to name: %w", err)
 		}
 	}
+	if len(columns) > 0 {
+		// Older schemas accidentally made namespace_id unique by itself, limiting
+		// a namespace to one repository. The model key is (namespace_id, name).
+		if _, err := engine.Exec("DROP INDEX IF EXISTS UQE_repo_cred"); err != nil {
+			return fmt.Errorf("drop legacy repo unique index: %w", err)
+		}
+		if _, err := engine.Exec("CREATE UNIQUE INDEX IF NOT EXISTS UQE_repo_cred ON repo (namespace_id, name)"); err != nil {
+			return fmt.Errorf("create repo unique index: %w", err)
+		}
+	}
 	return nil
 }