diff --git a/goldens/public-api/forms/forms.d.ts b/goldens/public-api/forms/forms.d.ts
index a2926bb425..e1d7c36544 100644
--- a/goldens/public-api/forms/forms.d.ts
+++ b/goldens/public-api/forms/forms.d.ts
@@ -6,7 +6,7 @@ export declare abstract class AbstractControl {
     get enabled(): boolean;
     readonly errors: ValidationErrors | null;
     get invalid(): boolean;
-    get parent(): FormGroup | FormArray;
+    get parent(): FormGroup | FormArray | null;
     get pending(): boolean;
     readonly pristine: boolean;
     get root(): AbstractControl;
diff --git a/packages/forms/src/model.ts b/packages/forms/src/model.ts
index f8c2558561..e3356e5726 100644
--- a/packages/forms/src/model.ts
+++ b/packages/forms/src/model.ts
@@ -173,8 +173,7 @@ export abstract class AbstractControl {
   // TODO(issue/24571): remove '!'.
   _updateOn!: FormHooks;
 
-  // TODO(issue/24571): remove '!'.
-  private _parent!: FormGroup|FormArray;
+  private _parent: FormGroup|FormArray|null = null;
   private _asyncValidationSubscription: any;
 
   /**
@@ -267,7 +266,7 @@ export abstract class AbstractControl {
   /**
    * The parent control.
    */
-  get parent(): FormGroup|FormArray {
+  get parent(): FormGroup|FormArray|null {
     return this._parent;
   }
 
@@ -1018,7 +1017,7 @@ export abstract class AbstractControl {
    */
   private _parentMarkedDirty(onlySelf?: boolean): boolean {
     const parentDirty = this._parent && this._parent.dirty;
-    return !onlySelf && parentDirty && !this._parent._anyControlsDirty();
+    return !onlySelf && !!parentDirty && !this._parent!._anyControlsDirty();
   }
 }