diff --git a/i18next/i18next.d.ts b/i18next/i18next.d.ts
index 3d24c9b96..060335af0 100644
--- a/i18next/i18next.d.ts
+++ b/i18next/i18next.d.ts
@@ -85,8 +85,8 @@ interface I18nextStatic {
         toLanguages(language: string): string[];
         regexEscape(str: string): string;
     };
-    init(callback?: (t: (key: string, options?: any) => string) => void ): JQueryDeferred<any>;
-    init(options?: I18nextOptions, callback?: (t: (key: string, options?: any) => string) => void ): JQueryDeferred<any>;
+    init(callback?: (err: any, t: (key: string, options?: any) => string) => void ): JQueryDeferred<any>;
+    init(options?: I18nextOptions, callback?: (err: any, t: (key: string, options?: any) => string) => void ): JQueryDeferred<any>;
     lng(): string;
     loadNamespace(namespace: string, callback?: () => void ): void;
     loadNamespaces(namespaces: string[], callback?: () => void ): void;
@@ -100,10 +100,10 @@ interface I18nextStatic {
         rules: any;
         setCurrentLng: (language: string) => void;
     };
-    preload(language: string, callback?: (t: (key: string, options?: any) => string) => void ): void;
-    preload(languages: string[], callback?: (t: (key: string, options?: any) => string) => void ): void;
+    preload(language: string, callback?: (err: any, t: (key: string, options?: any) => string) => void ): void;
+    preload(languages: string[], callback?: (err: any, t: (key: string, options?: any) => string) => void ): void;
     setDefaultNamespace(namespace: string): void;
-    setLng(language: string, callback?: (t: (key: string, options?: any) => string) => void ): void;
+    setLng(language: string, callback?: (err: any, t: (key: string, options?: any) => string) => void ): void;
     sync: {
         load: (languages: string[], options: I18nextOptions, callback: (err: Error, store: IResourceStore) => void ) => void;
         postMissing: (language: string, namespace: string, key: string, defaultValue: any, languages: string[]) => void;