diff --git a/packages/mdc-textfield/foundation.ts b/packages/mdc-textfield/foundation.ts
index 01cff4d5057..4b5e48b5082 100644
--- a/packages/mdc-textfield/foundation.ts
+++ b/packages/mdc-textfield/foundation.ts
@@ -112,7 +112,7 @@ class MDCTextFieldFoundation extends MDCFoundation<MDCTextFieldAdapter> {
    * @param adapter
    * @param foundationMap Map from subcomponent names to their subfoundations.
    */
-  constructor(adapter: MDCTextFieldAdapter, foundationMap: Partial<FoundationMapType> = {}) {
+  constructor(adapter?: Partial<MDCTextFieldAdapter>, foundationMap: Partial<FoundationMapType> = {}) {
     super({...MDCTextFieldFoundation.defaultAdapter, ...adapter});
 
     this.helperText_ = foundationMap.helperText;
diff --git a/test/unit/mdc-textfield/mdc-text-field.test.js b/test/unit/mdc-textfield/mdc-text-field.test.js
index 543fd12d157..435aa5d0a7b 100644
--- a/test/unit/mdc-textfield/mdc-text-field.test.js
+++ b/test/unit/mdc-textfield/mdc-text-field.test.js
@@ -30,8 +30,9 @@ import {MDCRipple} from '../../../packages/mdc-ripple/index';
 import {MDCLineRipple} from '../../../packages/mdc-line-ripple/index';
 import {MDCFloatingLabel} from '../../../packages/mdc-floating-label/index';
 import {MDCNotchedOutline} from '../../../packages/mdc-notched-outline/index';
-import {MDCTextField, MDCTextFieldFoundation, MDCTextFieldHelperText, MDCTextFieldCharacterCounter,
-  MDCTextFieldIcon} from '../../../packages/mdc-textfield/index';
+import {
+  MDCTextField, MDCTextFieldFoundation, MDCTextFieldHelperText, MDCTextFieldCharacterCounter, MDCTextFieldIcon,
+} from '../../../packages/mdc-textfield/index';
 import {cssClasses as helperTextCssClasses} from '../../../packages/mdc-textfield/helper-text/constants';
 import {cssClasses as characterCounterCssClasses} from '../../../packages/mdc-textfield/character-counter/constants';
 
@@ -467,9 +468,7 @@ test('#adapter.setLineRippleTransformOrigin calls the setRippleCenter method on
 function setupMockFoundationTest(root = getFixture()) {
   const MockFoundationConstructor = td.constructor(MDCTextFieldFoundation);
   const mockFoundation = new MockFoundationConstructor();
-  const component = new MDCTextField(
-    root,
-    mockFoundation);
+  const component = new MDCTextField(root, mockFoundation);
   return {root, component, mockFoundation};
 }