diff --git a/lodash/lodash-tests.ts b/lodash/lodash-tests.ts
index d2ab258f8..daf6ab099 100644
--- a/lodash/lodash-tests.ts
+++ b/lodash/lodash-tests.ts
@@ -7050,6 +7050,37 @@ module TestIsSafeInteger {
     }
 }
 
+// _.isSet
+module TestIsSet {
+    {
+        let value: number|Set<string>;
+
+        if (_.isSet<string>(value)) {
+            let result: Set<string> = value;
+        }
+        else {
+            let result: number = value;
+        }
+    }
+
+    {
+        let result: boolean;
+
+        result = _.isSet(any);
+        result = _(1).isSet();
+        result = _<any>([]).isSet();
+        result = _({}).isSet();
+    }
+
+    {
+        let result: _.LoDashExplicitWrapper<boolean>;
+
+        result = _(1).chain().isSet();
+        result = _<any>([]).chain().isSet();
+        result = _({}).chain().isSet();
+    }
+}
+
 // _.isString
 module TestIsString {
     {
diff --git a/lodash/lodash.d.ts b/lodash/lodash.d.ts
index ca523aad8..5285b0e6f 100644
--- a/lodash/lodash.d.ts
+++ b/lodash/lodash.d.ts
@@ -12132,6 +12132,31 @@ declare module _ {
         isSafeInteger(): LoDashExplicitWrapper<boolean>;
     }
 
+    //_.isSet
+    interface LoDashStatic {
+        /**
+         * Checks if value is classified as a Set object.
+         *
+         * @param value The value to check.
+         * @returns Returns true if value is correctly classified, else false.
+         */
+        isSet<T>(value?: any): value is Set<T>;
+    }
+
+    interface LoDashImplicitWrapperBase<T, TWrapper> {
+        /**
+         * @see _.isSet
+         */
+        isSet(): boolean;
+    }
+
+    interface LoDashExplicitWrapperBase<T, TWrapper> {
+        /**
+         * @see _.isSet
+         */
+        isSet(): LoDashExplicitWrapper<boolean>;
+    }
+
     //_.isString
     interface LoDashStatic {
         /**
@@ -18460,4 +18485,5 @@ declare module "lodash" {
 }
 
 // Backward compatibility with --target es5
+interface Set<T> {}
 interface Map<K, V> {}