diff --git a/packages/material-ui/src/Avatar/Avatar.d.ts b/packages/material-ui/src/Avatar/Avatar.d.ts
index 1b5ff82772f93b..a5ee8fe88f7e6b 100644
--- a/packages/material-ui/src/Avatar/Avatar.d.ts
+++ b/packages/material-ui/src/Avatar/Avatar.d.ts
@@ -16,7 +16,14 @@ export interface AvatarTypeMap<P = {}, D extends React.ElementType = 'div'> {
 
 declare const Avatar: OverridableComponent<AvatarTypeMap>;
 
-export type AvatarClassKey = 'root' | 'colorDefault' | 'circle' | 'rounded' | 'square' | 'img' | 'fallback';
+export type AvatarClassKey =
+  | 'root'
+  | 'colorDefault'
+  | 'circle'
+  | 'rounded'
+  | 'square'
+  | 'img'
+  | 'fallback';
 
 export type AvatarProps<
   D extends React.ElementType = AvatarTypeMap['defaultComponent'],