diff --git a/types/ismobilejs/index.d.ts b/types/ismobilejs/index.d.ts
index c0f7c4ec8b..18eee7ea1a 100644
--- a/types/ismobilejs/index.d.ts
+++ b/types/ismobilejs/index.d.ts
@@ -3,41 +3,55 @@
 // Definitions by: Maksim Karelov <https://github.com/Ty3uK>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
-export const any: boolean;
-export const phone: boolean;
-export const tablet: boolean;
-export const seven_inch: boolean;
+interface Apple {
+  phone: boolean;
+  ipod: boolean;
+  tablet: boolean;
+  device: boolean;
+}
 
-export const apple: {
-    phone: boolean;
-    ipod: boolean;
-    tablet: boolean;
-    device: boolean;
-};
+interface Android {
+  phone: boolean;
+  tablet: boolean;
+  device: boolean;
+}
 
-export const android: {
-    phone: boolean;
-    tablet: boolean;
-    device: boolean;
-};
+interface Amazon {
+  phone: boolean;
+  tablet: boolean;
+  device: boolean;
+}
 
-export const amazon: {
-    phone: boolean;
-    tablet: boolean;
-    device: boolean;
-};
+interface Windows {
+  phone: boolean;
+  tablet: boolean;
+  device: boolean;
+}
 
-export const windows: {
-    phone: boolean;
-    tablet: boolean;
-    device: boolean;
-};
+interface Other {
+  blackberry_10: boolean;
+  blackberry: boolean;
+  opera: boolean;
+  firefox: boolean;
+  chrome: boolean;
+  device: boolean;
+}
 
-export const other: {
-    blackberry_10: boolean;
-    blackberry: boolean;
-    opera: boolean;
-    firefox: boolean;
-    chrome: boolean;
-    device: boolean;
-};
+interface IsMobile {
+  any: boolean;
+  phone: boolean;
+  tablet: boolean;
+  seven_inch: boolean;
+
+  apple: Apple;
+  android: Android;
+  amazon: Amazon;
+  windows: Windows;
+  other: Other;
+
+  (userAgent?: string): IsMobile;
+}
+
+declare const isMobile: IsMobile;
+
+export = isMobile;
diff --git a/types/ismobilejs/ismobilejs-tests.ts b/types/ismobilejs/ismobilejs-tests.ts
index e69de29bb2..d53c674da9 100644
--- a/types/ismobilejs/ismobilejs-tests.ts
+++ b/types/ismobilejs/ismobilejs-tests.ts
@@ -0,0 +1,19 @@
+import * as isMobile from 'ismobilejs';
+
+const MOZILLA_ANDROID_UA  = 'Mozilla/5.0 (Android 4.4; Mobile; rv:41.0) Gecko/41.0 Firefox/41.0';
+const MOZILLA_IPHONE_UA   = 'Mozilla/5.0 (iPhone; CPU iPhone OS 8_3 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) FxiOS/1.0 Mobile/12F69 Safari/600.1.4';
+
+const CHROME_ANDROID_UA   = 'Mozilla/5.0 (Linux; Android 8.0.0; Pixel Build/OPP3.170518.006) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.66 Mobile Safari/537.36';
+const CHROME_IPHONE_UA    = 'Mozilla/5.0 (iPhone; CPU iPhone OS 10_3 like Mac OS X) AppleWebKit/602.1.50 (KHTML, like Gecko) CriOS/56.0.2924.75 Mobile/14E5239e Safari/602.1';
+
+// $ExpectType boolean
+isMobile(MOZILLA_ANDROID_UA).android.phone;
+// $ExpectType boolean
+isMobile(MOZILLA_IPHONE_UA).apple.phone;
+
+// $ExpectType boolean
+isMobile(CHROME_ANDROID_UA).android.phone;
+// $ExpectType boolean
+isMobile(CHROME_IPHONE_UA).apple.phone;
+
+console.log(isMobile.apple);
diff --git a/types/ismobilejs/tsconfig.json b/types/ismobilejs/tsconfig.json
index 3e3a1071d3..ae9975d94e 100644
--- a/types/ismobilejs/tsconfig.json
+++ b/types/ismobilejs/tsconfig.json
@@ -2,11 +2,13 @@
     "compilerOptions": {
         "module": "commonjs",
         "lib": [
-            "es6"
+            "es6",
+            "dom"
         ],
         "noImplicitAny": true,
         "noImplicitThis": true,
         "strictNullChecks": true,
+        "strictFunctionTypes": true,
         "baseUrl": "../",
         "typeRoots": [
             "../"