diff --git a/global.d.ts b/global.d.ts
new file mode 100644
index 0000000..d005f5b
--- /dev/null
+++ b/global.d.ts
@@ -0,0 +1,7 @@
+export {};
+
+declare global {
+  interface Window {
+    GM_fetch: typeof fetch; // or a more specific custom type
+  }
+}
\ No newline at end of file
diff --git a/tsconfig.json b/tsconfig.json
index d459c51..8282a68 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,4 +1,5 @@
 {
+  "include": ["src/**/*", "declarations.d.ts", "global.d.ts"],
   "compilerOptions": {
     "outDir": "./dist/",
     "noImplicitAny": true,