diff --git a/src/index.d.ts b/src/index.d.ts
new file mode 100644
index 0000000..789e9e3
--- /dev/null
+++ b/src/index.d.ts
@@ -0,0 +1,9 @@
+export {};
+
+declare global {
+  namespace Express {
+    export interface Request {
+      planetId?: string;
+    }
+  }
+}