diff --git a/src/driver/mysql/MysqlQueryRunner.ts b/src/driver/mysql/MysqlQueryRunner.ts
index 0e29a0a1d..9cbc3e24b 100644
--- a/src/driver/mysql/MysqlQueryRunner.ts
+++ b/src/driver/mysql/MysqlQueryRunner.ts
@@ -51,7 +51,7 @@ export class MysqlQueryRunner extends BaseQueryRunner implements QueryRunner {
      */
     protected databaseConnectionPromise!: Promise<[Connection, () => Promise<void>]>;
 
-    protected databaseConnection!: [Connection, () => Promise<void>];
+    declare protected databaseConnection: [Connection, () => Promise<void>];
 
     // -------------------------------------------------------------------------
     // Constructor
diff --git a/src/driver/postgres/PostgresQueryRunner.ts b/src/driver/postgres/PostgresQueryRunner.ts
index 0f91081b5..1fc57a103 100644
--- a/src/driver/postgres/PostgresQueryRunner.ts
+++ b/src/driver/postgres/PostgresQueryRunner.ts
@@ -54,7 +54,7 @@ export class PostgresQueryRunner extends BaseQueryRunner implements QueryRunner
      */
     protected releaseCallback!: () => Promise<void>;
 
-    protected databaseConnection!: PoolClient;
+   declare  protected databaseConnection: PoolClient;
 
     // -------------------------------------------------------------------------
     // Constructor
diff --git a/src/driver/sqlite/SqliteDriver.ts b/src/driver/sqlite/SqliteDriver.ts
index 08a2ddc39..06e594e22 100644
--- a/src/driver/sqlite/SqliteDriver.ts
+++ b/src/driver/sqlite/SqliteDriver.ts
@@ -26,9 +26,9 @@ export class SqliteDriver extends AbstractSqliteDriver {
      */
     options: SqliteConnectionOptions;
 
-    databaseConnection!: DB;
+    declare databaseConnection: DB;
 
-    sqlite!: DenoSqlite;
+    declare sqlite: DenoSqlite;
 
 
     // -------------------------------------------------------------------------
diff --git a/src/driver/sqljs/SqljsDriver.ts b/src/driver/sqljs/SqljsDriver.ts
index 180015f17..5778f93bd 100644
--- a/src/driver/sqljs/SqljsDriver.ts
+++ b/src/driver/sqljs/SqljsDriver.ts
@@ -20,7 +20,7 @@ declare var window: Window;
 
 export class SqljsDriver extends AbstractSqliteDriver implements AutoSavableDriver {
     // The driver specific options.
-    options!: SqljsConnectionOptions;
+    declare options: SqljsConnectionOptions;
 
     // -------------------------------------------------------------------------
     // Constructor
diff --git a/src/repository/MongoRepository.ts b/src/repository/MongoRepository.ts
index cadc5dc53..57c1aa1cb 100644
--- a/src/repository/MongoRepository.ts
+++ b/src/repository/MongoRepository.ts
@@ -48,7 +48,7 @@ export class MongoRepository<Entity extends ObjectLiteral> extends Repository<En
     /**
      * Entity Manager used by this repository.
      */
-    readonly manager!: MongoEntityManager;
+    declare readonly manager: MongoEntityManager;
 
     // -------------------------------------------------------------------------
     // Overridden Methods