diff --git a/types/classnames/classnames-tests.ts b/types/classnames/classnames-tests.ts
index b2b8c9eba4..55b801eb40 100644
--- a/types/classnames/classnames-tests.ts
+++ b/types/classnames/classnames-tests.ts
@@ -38,3 +38,6 @@ const className = cx('foo', ['bar'], { baz: true }); // => "abc def xyz"
 
 // falsey values are just ignored
 cx(null, 'bar', undefined, 0, 1, { baz: null }, ''); // => 'bar 1'
+
+// true is just ignored
+cx(true || "foo");
diff --git a/types/classnames/index.d.ts b/types/classnames/index.d.ts
index ce2abb5ee3..40e3ce835c 100644
--- a/types/classnames/index.d.ts
+++ b/types/classnames/index.d.ts
@@ -9,7 +9,7 @@
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.3
 
-type ClassValue = string | number | ClassDictionary | ClassArray | undefined | null | false;
+type ClassValue = string | number | ClassDictionary | ClassArray | undefined | null | boolean;
 
 interface ClassDictionary {
 	[id: string]: boolean | undefined | null;