diff --git a/src/fmt/doc.go b/src/fmt/doc.go
index f8ae4e72f9..a2faecb36e 100644
--- a/src/fmt/doc.go
+++ b/src/fmt/doc.go
@@ -174,6 +174,9 @@
 	that type has a String method. Such pathologies are rare, however,
 	and the package does not protect against them.
 
+	When printing a struct, fmt cannot and therefore does not invoke
+	formatting methods such as Error or String on unexported fields.
+
 	Explicit argument indexes:
 
 	In Printf, Sprintf, and Fprintf, the default behavior is for each