diff --git a/docs/advanced.md b/docs/advanced.md
index c3c54614..59251706 100644
--- a/docs/advanced.md
+++ b/docs/advanced.md
@@ -1095,6 +1095,11 @@ instantiation of the test suite. The next argument is the name of the test
 pattern, and the last is the
 [parameter generator](reference/testing.md#param-generators).
 
+The parameter generator expression is not evaluated until GoogleTest is
+initialized (via `InitGoogleTest()`). Any prior initialization done in the
+`main` function will be accessible from the parameter generator, for example,
+the results of flag parsing.
+
 You can instantiate a test pattern more than once, so to distinguish different
 instances of the pattern, the instantiation name is added as a prefix to the
 actual test suite name. Remember to pick unique prefixes for different