diff --git a/lodash/lodash-tests.ts b/lodash/lodash-tests.ts
index ff3061a1f..ba1540055 100644
--- a/lodash/lodash-tests.ts
+++ b/lodash/lodash-tests.ts
@@ -6607,17 +6607,47 @@ module TestIsEqual {
 }
 
 // _.isError
-result = <boolean>_.isError(any);
-result = <boolean>_(1).isError();
-result = <boolean>_<any>([]).isError();
-result = <boolean>_({}).isError();
-{
-  let value: Error|string = "error";
-  if (_.isError(value)) {
-    let message: string = value.message;
-  } else {
-    let message: string = value;
-  }
+module TestIsError {
+    {
+        let value: number|Error;
+
+        if (_.isError(value)) {
+            let result: Error = value;
+        }
+        else {
+            let result: number = value;
+        }
+    }
+
+    {
+        class CustomError extends Error {}
+
+        let value: number|CustomError;
+
+        if (_.isError(value)) {
+            let result: CustomError = value;
+        }
+        else {
+            let result: number = value;
+        }
+    }
+
+    {
+        let result: boolean;
+
+        result = _.isError(any);
+        result = _(1).isError();
+        result = _<any>([]).isError();
+        result = _({}).isError();
+    }
+
+    {
+        let result: _.LoDashExplicitWrapper<boolean>;
+
+        result = _(1).chain().isError();
+        result = _<any>([]).chain().isError();
+        result = _({}).chain().isError();
+    }
 }
 
 // _.isFinite
diff --git a/lodash/lodash.d.ts b/lodash/lodash.d.ts
index 7354d0e63..dc8298ab6 100644
--- a/lodash/lodash.d.ts
+++ b/lodash/lodash.d.ts
@@ -10504,6 +10504,7 @@ declare module _ {
         /**
          * Checks if value is an Error, EvalError, RangeError, ReferenceError, SyntaxError, TypeError, or URIError
          * object.
+         *
          * @param value The value to check.
          * @return Returns true if value is an error object, else false.
          */
@@ -10517,6 +10518,13 @@ declare module _ {
         isError(): boolean;
     }
 
+    interface LoDashExplicitWrapperBase<T, TWrapper> {
+        /**
+         * @see _.isError
+         */
+        isError(): LoDashExplicitWrapper<boolean>;
+    }
+
     //_.isFinite
     interface LoDashStatic {
         /**