diff --git a/types/cosmiconfig/cosmiconfig-tests.ts b/types/cosmiconfig/cosmiconfig-tests.ts
index 632569c6f9..508ad00aa0 100644
--- a/types/cosmiconfig/cosmiconfig-tests.ts
+++ b/types/cosmiconfig/cosmiconfig-tests.ts
@@ -11,8 +11,12 @@ const explorer = cosmiconfig("yourModuleName", {
   ignoreEmptySearchPlaces: false,
 });
 
+const explorer2 = cosmiconfig("yourModuleName");
+
 Promise.all([
+  explorer.search(),
   explorer.search(path.join(__dirname)),
+  explorer.searchSync(),
   explorer.searchSync(path.join(__dirname)),
   explorer.load(path.join(__dirname, "sample-config.json")),
   explorer.loadSync(path.join(__dirname, "sample-config.json")),
diff --git a/types/cosmiconfig/index.d.ts b/types/cosmiconfig/index.d.ts
index bdafc922ec..eb876b6ef2 100644
--- a/types/cosmiconfig/index.d.ts
+++ b/types/cosmiconfig/index.d.ts
@@ -2,6 +2,7 @@
 // Project: https://github.com/davidtheclark/cosmiconfig
 // Definitions by: ozum <https://github.com/ozum>
 //                 szeck87 <https://github.com/szeck87>
+//                 saadq <https://github.com/saadq>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.2
 
@@ -35,8 +36,8 @@ export interface Loaders {
 }
 
 export interface Explorer {
-  search(searchFrom: string): Promise<null | CosmiconfigResult>;
-  searchSync(searchFrom: string): null | CosmiconfigResult;
+  search(searchFrom?: string): Promise<null | CosmiconfigResult>;
+  searchSync(searchFrom?: string): null | CosmiconfigResult;
   load(loadPath: string): Promise<CosmiconfigResult>;
   loadSync(loadPath: string): CosmiconfigResult;
   clearLoadCache(): void;
@@ -55,4 +56,4 @@ export interface ExplorerOptions {
   ignoreEmptySearchPlaces?: boolean;
 }
 
-export default function cosmiconfig(moduleName: string, options: ExplorerOptions): Explorer;
+export default function cosmiconfig(moduleName: string, options?: ExplorerOptions): Explorer;