diff --git a/packages/block-library/src/avatar/hooks.js b/packages/block-library/src/avatar/hooks.js
index fcc7090547b14f..4394fd65a6da82 100644
--- a/packages/block-library/src/avatar/hooks.js
+++ b/packages/block-library/src/avatar/hooks.js
@@ -76,12 +76,14 @@ export function useUserAvatar( { userId, postId, postType } ) {
 		},
 		[ postType, postId, userId ]
 	);
-	const avatarUrls = authorDetails
-		? Object.values( authorDetails.avatar_urls )
-		: null;
-	const sizes = authorDetails
-		? Object.keys( authorDetails.avatar_urls )
-		: null;
+	const avatarUrls =
+		authorDetails && authorDetails.avatar_urls !== undefined
+			? Object.values( authorDetails.avatar_urls )
+			: null;
+	const sizes =
+		authorDetails && authorDetails.avatar_urls !== undefined
+			? Object.keys( authorDetails.avatar_urls )
+			: null;
 	const { minSize, maxSize } = getAvatarSizes( sizes );
 	const defaultAvatar = useDefaultAvatar();
 	return {