diff --git a/foundation/foundation.d.ts b/foundation/foundation.d.ts
index a51e47ae9..ce782fd92 100644
--- a/foundation/foundation.d.ts
+++ b/foundation/foundation.d.ts
@@ -304,6 +304,16 @@ declare module Foundation {
             add_custom_rule(rule : string, media : string) : void;
             image_loaded(images : JQuery, callback : (...args : any[]) => any) : void;
             random_str(length? : number) : string;
+            is_small_only(): boolean;
+            is_small_up(): boolean;
+            is_medium_only(): boolean;
+            is_medium_up(): boolean;
+            is_large_only(): boolean;
+            is_large_up(): boolean;
+            is_xlarge_only(): boolean;
+            is_xlarge_up(): boolean;
+            is_xxlarge_only(): boolean;
+            is_xxlarge_up(): boolean;
         };
     }
 }