diff --git a/packages/mysql/src/mysql-platform.ts b/packages/mysql/src/mysql-platform.ts
index 7fc200564..0edf608f8 100644
--- a/packages/mysql/src/mysql-platform.ts
+++ b/packages/mysql/src/mysql-platform.ts
@@ -10,17 +10,7 @@
 
 import { Pool } from 'mariadb';
 import { mySqlSerializer } from './mysql-serializer.js';
-import {
-    isDateType,
-    isReferenceType,
-    isUUIDType,
-    ReflectionClass,
-    ReflectionKind,
-    ReflectionProperty,
-    Serializer,
-    Type,
-    TypeNumberBrand,
-} from '@deepkit/type';
+import { isReferenceType, isUUIDType, ReflectionClass, ReflectionKind, ReflectionProperty, Serializer, Type, TypeNumberBrand } from '@deepkit/type';
 import {
     Column,
     DefaultPlatform,
@@ -30,6 +20,7 @@ import {
     PreparedAdapter,
     typeResolvesToBigInt,
     typeResolvesToBoolean,
+    typeResolvesToDate,
     typeResolvesToInteger,
     typeResolvesToNumber,
     typeResolvesToString,
@@ -78,7 +69,7 @@ export class MySQLPlatform extends DefaultPlatform {
         this.addType(type => type.kind === ReflectionKind.number && type.brand === TypeNumberBrand.float64, 'double');
         this.addType(type => type.kind === ReflectionKind.number && type.brand === TypeNumberBrand.float, 'double');
 
-        this.addType(isDateType, 'datetime');
+        this.addType(typeResolvesToDate, 'datetime');
         this.addType(isUUIDType, 'binary', 16);
 
         this.addBinaryType('longblob');
diff --git a/packages/mysql/tests/mysql.spec.ts b/packages/mysql/tests/mysql.spec.ts
index f7d73e50d..69635665b 100644
--- a/packages/mysql/tests/mysql.spec.ts
+++ b/packages/mysql/tests/mysql.spec.ts
@@ -324,21 +324,23 @@ test('unique constraint 1', async () => {
     }
 });
 
-test('string/null unions should not render as JSON', async () => {
+test('non-object null unions should not render as JSON', async () => {
     @entity.name('model6')
     class Model {
         id: number & PrimaryKey & AutoIncrement = 0;
 
-        constructor(public name: string, public nickName: string | null = null) {}
+        constructor(public name: string, public nickName: string | null = null, public birthdate: Date | null = null) {}
     }
 
     const database = await databaseFactory([Model]);
     await database.persist(new Model('Peter'));
     await database.persist(new Model('Christopher', 'Chris'));
+    await database.persist(new Model('Thomas', 'Tom', new Date('1960-02-10T00:00:00Z')));
 
     const result = await database.query(Model).orderBy('id', 'asc').find();
     expect(result).toMatchObject([
         {name: 'Peter', nickName: null},
-        {name: 'Christopher', nickName: 'Chris'}
+        {name: 'Christopher', nickName: 'Chris'},
+        {name: 'Thomas', nickName: 'Tom', birthdate: new Date('1960-02-10T00:00:00Z')},
     ]);
 });
diff --git a/packages/sql/src/platform/default-platform.ts b/packages/sql/src/platform/default-platform.ts
index ad9615584..dd08967e2 100644
--- a/packages/sql/src/platform/default-platform.ts
+++ b/packages/sql/src/platform/default-platform.ts
@@ -24,17 +24,7 @@ import { sqlSerializer } from '../serializer/sql-serializer.js';
 import { parseType, SchemaParser } from '../reverse/schema-parser.js';
 import { SQLFilterBuilder } from '../sql-filter-builder.js';
 import { Sql } from '../sql-builder.js';
-import {
-    binaryTypes,
-    databaseAnnotation,
-    isCustomTypeClass,
-    isIntegerType,
-    ReflectionClass,
-    ReflectionKind,
-    ReflectionProperty,
-    Serializer,
-    Type,
-} from '@deepkit/type';
+import { binaryTypes, databaseAnnotation, isCustomTypeClass, isDateType, isIntegerType, ReflectionClass, ReflectionKind, ReflectionProperty, Serializer, Type } from '@deepkit/type';
 import { DatabaseEntityRegistry, MigrateOptions } from '@deepkit/orm';
 import { splitDotPath } from '../sql-adapter.js';
 import { PreparedAdapter } from '../prepare.js';
@@ -98,6 +88,11 @@ export function typeResolvesToBoolean(type: Type): boolean {
     return false;
 }
 
+export function typeResolvesToDate(type: Type): boolean {
+    if (type.kind === ReflectionKind.union) return type.types.filter(isNonUndefined).every(isDateType);
+    return isDateType(type);
+}
+
 export function noopSqlTypeCaster(placeholder: string): string {
     return placeholder;
 }