diff --git a/docs/advanced.md b/docs/advanced.md
index aea4feec..f2f8854b 100644
--- a/docs/advanced.md
+++ b/docs/advanced.md
@@ -926,9 +926,11 @@ class FooTest : public testing::Test {
   void TearDown() override { ... }
 
   // Some expensive resource shared by all tests.
-  static T* shared_resource_ = nullptr;
+  static T* shared_resource_;
 };
 
+T* FooTest::shared_resource_ = nullptr;
+
 TEST_F(FooTest, Test1) {
   ... you can refer to shared_resource_ here ...
 }