diff --git a/lodash/lodash-tests.ts b/lodash/lodash-tests.ts
index 2d244b16e..9cf772cab 100644
--- a/lodash/lodash-tests.ts
+++ b/lodash/lodash-tests.ts
@@ -5532,17 +5532,34 @@ result = <boolean>_<any>([]).isFinite();
 result = <boolean>_({}).isFinite();
 
 // _.isFunction
-result = <boolean>_.isFunction(any);
-result = <boolean>_(1).isFunction();
-result = <boolean>_<any>([]).isFunction();
-result = <boolean>_({}).isFunction();
-{
-  let value: Function|string = "foo";
-  if (_.isFunction(value)) {
-    value();
-  } else {
-    let result: string = value;
-  }
+module TestIsFunction {
+    {
+        let value: number|Function;
+
+        if (_.isFunction(value)) {
+            let result: Function = value;
+        }
+        else {
+            let result: number = value;
+        }
+    }
+
+    {
+        let result: boolean;
+
+        result = _.isFunction(any);
+        result = _(1).isFunction();
+        result = _<any>([]).isFunction();
+        result = _({}).isFunction();
+    }
+
+    {
+        let result: _.LoDashExplicitWrapper<boolean>;
+
+        result = _(1).chain().isFunction();
+        result = _<any>([]).chain().isFunction();
+        result = _({}).chain().isFunction();
+    }
 }
 
 // _.isMatch
diff --git a/lodash/lodash.d.ts b/lodash/lodash.d.ts
index 8425f1d82..81d78b1bc 100644
--- a/lodash/lodash.d.ts
+++ b/lodash/lodash.d.ts
@@ -9434,9 +9434,10 @@ declare module _ {
     interface LoDashStatic {
         /**
          * Checks if value is classified as a Function object.
+         *
          * @param value The value to check.
          * @return Returns true if value is correctly classified, else false.
-         **/
+         */
         isFunction(value?: any): value is Function;
     }
 
@@ -9447,6 +9448,13 @@ declare module _ {
         isFunction(): boolean;
     }
 
+    interface LoDashExplicitWrapperBase<T, TWrapper> {
+        /**
+         * @see _.isFunction
+         */
+        isFunction(): LoDashExplicitWrapper<boolean>;
+    }
+
     //_.isMatch
     interface isMatchCustomizer {
         (value: any, other: any, indexOrKey?: number|string): boolean;