diff --git a/types/sanitize-html/index.d.ts b/types/sanitize-html/index.d.ts
index 5e5e9ab2a3..5584eada56 100644
--- a/types/sanitize-html/index.d.ts
+++ b/types/sanitize-html/index.d.ts
@@ -57,7 +57,7 @@ declare namespace sanitize {
   interface IOptions {
     allowedAttributes?: { [index: string]: AllowedAttribute[] } | boolean;
     allowedStyles?:  { [index: string]: { [index: string]: RegExp[] } };
-    allowedClasses?: { [index: string]: string[] } | boolean;
+    allowedClasses?: { [index: string]: string[] | boolean };
     allowedIframeHostnames?: string[];
     allowIframeRelativeUrls?: boolean;
     allowedSchemes?: string[] | boolean;
diff --git a/types/sanitize-html/sanitize-html-tests.ts b/types/sanitize-html/sanitize-html-tests.ts
index ef6741c9cb..2f1126b389 100644
--- a/types/sanitize-html/sanitize-html-tests.ts
+++ b/types/sanitize-html/sanitize-html-tests.ts
@@ -6,6 +6,10 @@ let options: sanitize.IOptions = {
     'a': sanitize.defaults.allowedAttributes['a'].concat('rel'),
     'img': ['src', 'height', 'width', 'alt', 'style']
   },
+  allowedClasses: {
+    a: ['className'],
+    p: false,
+  },
   allowedStyles: {
     '*': {
         color: [/^red$/],