diff --git a/package.json b/package.json
index 95e3a7c..1448901 100644
--- a/package.json
+++ b/package.json
@@ -125,7 +125,7 @@
     "prettier": "^2.1.2",
     "rimraf": "^3.0.0",
     "ts-jest": "^25.2.1",
-    "typescript": "^4.1.2",
+    "typescript": "^4.8.2",
     "umi-plugin-hire": "^1.0.3"
   }
 }
diff --git a/src/prefetch.ts b/src/prefetch.ts
index f4a47f4..6af7697 100644
--- a/src/prefetch.ts
+++ b/src/prefetch.ts
@@ -31,6 +31,16 @@ const requestIdleCallback =
     }, 1);
   };
 
+declare global {
+  interface Navigator {
+    connection: {
+      saveData: boolean;
+      effectiveType: string;
+      type: 'bluetooth' | 'cellular' | 'ethernet' | 'none' | 'wifi' | 'wimax' | 'other' | 'unknown';
+    };
+  }
+}
+
 const isSlowNetwork = navigator.connection
   ? navigator.connection.saveData ||
     (navigator.connection.type !== 'wifi' &&