diff --git a/types/is-svg/index.d.ts b/types/is-svg/index.d.ts
index 21e85cd2e2..54ebb84457 100644
--- a/types/is-svg/index.d.ts
+++ b/types/is-svg/index.d.ts
@@ -1,8 +1,13 @@
-// Type definitions for is-svg 2.1
+// Type definitions for is-svg 3.0
 // Project: https://github.com/sindresorhus/is-svg#readme
 // Definitions by: BendingBender <https://github.com/BendingBender>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
-export = isSvg;
+/// <reference types="node" />
 
-declare function isSvg(input: string): boolean;
+declare function isSvg(input?: string | Buffer | false | null): boolean;
+
+// So that `import * as X` is possible
+declare namespace isSvg {}
+
+export = isSvg;
diff --git a/types/is-svg/is-svg-tests.ts b/types/is-svg/is-svg-tests.ts
index d556a944f9..73ba29062c 100644
--- a/types/is-svg/is-svg-tests.ts
+++ b/types/is-svg/is-svg-tests.ts
@@ -1,3 +1,11 @@
-import isSvg = require('is-svg');
+import * as isSvg from 'is-svg';
 
-const result: boolean = isSvg('<svg xmlns="http://www.w3.org/2000/svg"><path fill="#00CD9F"/></svg>');
+const data = '<svg></svg>';
+let result = false;
+
+result = isSvg(data);
+result = isSvg(Buffer.from(data));
+result = isSvg(false);
+result = isSvg(null);
+result = isSvg(undefined);
+result = isSvg();