diff --git a/i18next.d.ts b/i18next.d.ts
new file mode 100644
index 00000000..adf77720
--- /dev/null
+++ b/i18next.d.ts
@@ -0,0 +1,7 @@
+import "i18next";
+
+declare module "i18next" {
+  interface CustomTypeOptions {
+    returnNull: false;
+  }
+}
diff --git a/next-i18next.config.js b/next-i18next.config.js
index 41d447db..76c3d3b5 100644
--- a/next-i18next.config.js
+++ b/next-i18next.config.js
@@ -10,4 +10,5 @@ module.exports = {
     typeof window === "undefined"
       ? require("path").resolve("./public/locales")
       : "/public/locales",
+  returnNull: false,
 };