diff --git a/packages/entity/src/EntityFields.ts b/packages/entity/src/EntityFields.ts
index 59a7a0ab..57aaf246 100644
--- a/packages/entity/src/EntityFields.ts
+++ b/packages/entity/src/EntityFields.ts
@@ -111,67 +111,67 @@ export abstract class EntityFieldDefinition<T> {
   }
 
   /**
-   * Validates input value for a field of this type. Null is considered valid. This is used for things like:
+   * Validates input value for a field of this type. Null and undefined are considered valid by default. This is used for things like:
    * - EntityLoader.loadByFieldValue - to ensure the value being loaded by is a valid value
    * - EntityMutator.setField - to ensure the value being set is a valid value
    */
-  public validateInputValueIfNotNull(value: T | null): boolean {
-    if (value === null) {
+  public validateInputValue(value: T | null | undefined): boolean {
+    if (value === null || value === undefined) {
       return true;
     }
 
-    return this.validateInputValue(value);
+    return this.validateInputValueInternal(value);
   }
-  protected abstract validateInputValue(value: T): boolean;
+  protected abstract validateInputValueInternal(value: T): boolean;
 }
 
 export class StringField extends EntityFieldDefinition<string> {
-  protected validateInputValue(value: string): boolean {
+  protected validateInputValueInternal(value: string): boolean {
     return typeof value === 'string';
   }
 }
 export class UUIDField extends StringField {
-  protected validateInputValue(value: string): boolean {
+  protected validateInputValueInternal(value: string): boolean {
     return validateUUID(value);
   }
 }
 export class DateField extends EntityFieldDefinition<Date> {
-  protected validateInputValue(value: Date): boolean {
+  protected validateInputValueInternal(value: Date): boolean {
     return value instanceof Date;
   }
 }
 export class BooleanField extends EntityFieldDefinition<boolean> {
-  protected validateInputValue(value: boolean): boolean {
+  protected validateInputValueInternal(value: boolean): boolean {
     return typeof value === 'boolean';
   }
 }
 export class NumberField extends EntityFieldDefinition<number> {
-  protected validateInputValue(value: number): boolean {
+  protected validateInputValueInternal(value: number): boolean {
     return typeof value === 'number';
   }
 }
 export class StringArrayField extends EntityFieldDefinition<string[]> {
-  protected validateInputValue(value: string[]): boolean {
+  protected validateInputValueInternal(value: string[]): boolean {
     return Array.isArray(value) && value.every((subValue) => typeof subValue === 'string');
   }
 }
 export class JSONObjectField extends EntityFieldDefinition<object> {
-  protected validateInputValue(value: object): boolean {
+  protected validateInputValueInternal(value: object): boolean {
     return typeof value === 'object' && !Array.isArray(value);
   }
 }
 export class EnumField extends EntityFieldDefinition<string | number> {
-  protected validateInputValue(value: string | number): boolean {
+  protected validateInputValueInternal(value: string | number): boolean {
     return typeof value === 'number' || typeof value === 'string';
   }
 }
 export class JSONArrayField extends EntityFieldDefinition<any[]> {
-  protected validateInputValue(value: any[]): boolean {
+  protected validateInputValueInternal(value: any[]): boolean {
     return Array.isArray(value);
   }
 }
 export class MaybeJSONArrayField extends EntityFieldDefinition<any | any[]> {
-  protected validateInputValue(_value: any): boolean {
+  protected validateInputValueInternal(_value: any): boolean {
     return true;
   }
 }
diff --git a/packages/entity/src/EntityLoader.ts b/packages/entity/src/EntityLoader.ts
index 9e95958c..49190586 100644
--- a/packages/entity/src/EntityLoader.ts
+++ b/packages/entity/src/EntityLoader.ts
@@ -336,7 +336,7 @@ export default class EntityLoader<
     const fieldDefinition = this.entityConfiguration.schema.get(fieldName);
     invariant(fieldDefinition, `must have field definition for field = ${fieldName}`);
     for (const fieldValue of fieldValues) {
-      const isInputValid = fieldDefinition.validateInputValueIfNotNull(fieldValue);
+      const isInputValid = fieldDefinition.validateInputValue(fieldValue);
       if (!isInputValid) {
         throw new EntityInvalidFieldValueError(this.entityClass, fieldName, fieldValue);
       }
diff --git a/packages/entity/src/EntityMutator.ts b/packages/entity/src/EntityMutator.ts
index a7fdac87..b584364a 100644
--- a/packages/entity/src/EntityMutator.ts
+++ b/packages/entity/src/EntityMutator.ts
@@ -79,7 +79,7 @@ abstract class BaseMutator<
       const fieldValue = fields[fieldName];
       const fieldDefinition = this.entityConfiguration.schema.get(fieldName);
       invariant(fieldDefinition, `must have field definition for field = ${fieldName}`);
-      const isInputValid = fieldDefinition.validateInputValueIfNotNull(fieldValue);
+      const isInputValid = fieldDefinition.validateInputValue(fieldValue);
       if (!isInputValid) {
         throw new EntityInvalidFieldValueError(this.entityClass, fieldName, fieldValue);
       }
diff --git a/packages/entity/src/__tests__/EntityFields-test.ts b/packages/entity/src/__tests__/EntityFields-test.ts
index 81e37449..1875f659 100644
--- a/packages/entity/src/__tests__/EntityFields-test.ts
+++ b/packages/entity/src/__tests__/EntityFields-test.ts
@@ -15,7 +15,7 @@ import {
 } from '../EntityFields';
 
 class TestFieldDefinition extends EntityFieldDefinition<string> {
-  protected validateInputValue(value: string): boolean {
+  protected validateInputValueInternal(value: string): boolean {
     return value === 'helloworld';
   }
 }
@@ -33,17 +33,22 @@ describe(EntityFieldDefinition, () => {
 
   test('validator returns true when value is null', () => {
     const fieldDefinition = new TestFieldDefinition({ columnName: 'wat', cache: true });
-    expect(fieldDefinition.validateInputValueIfNotNull(null)).toBe(true);
+    expect(fieldDefinition.validateInputValue(null)).toBe(true);
+  });
+
+  test('validator returns true when value is undefined', () => {
+    const fieldDefinition = new TestFieldDefinition({ columnName: 'wat', cache: true });
+    expect(fieldDefinition.validateInputValue(undefined)).toBe(true);
   });
 
   test('validator returns false when value is invalid', () => {
     const fieldDefinition = new TestFieldDefinition({ columnName: 'wat', cache: true });
-    expect(fieldDefinition.validateInputValueIfNotNull('nothelloworld')).toBe(false);
+    expect(fieldDefinition.validateInputValue('nothelloworld')).toBe(false);
   });
 
   test('validator returns true when value is valid', () => {
     const fieldDefinition = new TestFieldDefinition({ columnName: 'wat', cache: true });
-    expect(fieldDefinition.validateInputValueIfNotNull('helloworld')).toBe(true);
+    expect(fieldDefinition.validateInputValue('helloworld')).toBe(true);
   });
 });
 
@@ -55,13 +60,13 @@ const describeFieldTestCase = <T>(
   describe(fieldDefinition.constructor.name, () => {
     if (validValues.length > 0) {
       test.each(validValues)(`${fieldDefinition.constructor.name}.valid %p`, (value) => {
-        expect(fieldDefinition.validateInputValueIfNotNull(value)).toBe(true);
+        expect(fieldDefinition.validateInputValue(value)).toBe(true);
       });
     }
 
     if (invalidValues.length > 0) {
       test.each(invalidValues)(`${fieldDefinition.constructor.name}.invalid %p`, (value) => {
-        expect(fieldDefinition.validateInputValueIfNotNull(value)).toBe(false);
+        expect(fieldDefinition.validateInputValue(value)).toBe(false);
       });
     }
   });