diff --git a/types/tether/index.d.ts b/types/tether/index.d.ts
index 20de5d7bf0..69cc2b0ef9 100644
--- a/types/tether/index.d.ts
+++ b/types/tether/index.d.ts
@@ -24,7 +24,7 @@ declare namespace Tether {
     interface ITetherOptions {
         attachment: string;
         bodyElement?: HTMLElement;
-        classes?: {[className: string]: boolean};
+        classes?: {[className: string]: boolean | string};
         classPrefix?: string;
         constraints?: ITetherConstraint[];
         element?: HTMLElement | string | any /* JQuery */;
diff --git a/types/tether/tether-tests.ts b/types/tether/tether-tests.ts
index 5f78bb3b99..0675ed9594 100644
--- a/types/tether/tether-tests.ts
+++ b/types/tether/tether-tests.ts
@@ -9,7 +9,11 @@ new Tether({
     targetAttachment: "top middle",
     targetModifier: "visible",
     offset: "-15px 0",
-    targetOffset: "0 0"
+    targetOffset: "0 0",
+    classes: {
+      'element': false,
+      'target': 'someClassName'
+    }
 });
 
 new Tether({
@@ -50,4 +54,3 @@ new Tether({
         }
     ]
 });
-