diff --git a/src/persistence/SubjectExecutor.ts b/src/persistence/SubjectExecutor.ts
index e40d68cdac..0af1a7d0cf 100644
--- a/src/persistence/SubjectExecutor.ts
+++ b/src/persistence/SubjectExecutor.ts
@@ -551,7 +551,7 @@ export class SubjectExecutor {
 
             // for mongodb we have a bit different updation logic
             if (this.queryRunner instanceof MongoQueryRunner) {
-                const partialEntity = OrmUtils.mergeDeep({}, subject.entity!);
+                const partialEntity = OrmUtils.mergeDeep({}, subject.entity);
                 if (subject.metadata.objectIdColumn && subject.metadata.objectIdColumn.propertyName) {
                     delete partialEntity[subject.metadata.objectIdColumn.propertyName];
                 }
@@ -631,7 +631,7 @@ export class SubjectExecutor {
 
             // for mongodb we have a bit different updation logic
             if (this.queryRunner instanceof MongoQueryRunner) {
-                const partialEntity = OrmUtils.mergeDeep({}, subject.entity!);
+                const partialEntity = OrmUtils.mergeDeep({}, subject.entity);
                 if (subject.metadata.objectIdColumn && subject.metadata.objectIdColumn.propertyName) {
                     delete partialEntity[subject.metadata.objectIdColumn.propertyName];
                 }
diff --git a/src/util/OrmUtils.ts b/src/util/OrmUtils.ts
index c64486f1f9..32cd470f62 100644
--- a/src/util/OrmUtils.ts
+++ b/src/util/OrmUtils.ts
@@ -104,7 +104,7 @@ export class OrmUtils {
     }
 
     /**
-     * Deep Object.assign for simple objects.
+     * Deep Object.assign.
      */
     static mergeDeep(target: any, ...sources: any[]): any {
         if (!sources.length) {