diff --git a/src/fmt/doc.go b/src/fmt/doc.go
index 9dc2a0d75d..9ba11f4a2b 100644
--- a/src/fmt/doc.go
+++ b/src/fmt/doc.go
@@ -225,7 +225,9 @@
 		%!s(PANIC=bad)
 
 	The %!s just shows the print verb in use when the failure
-	occurred.
+	occurred. If the panic is caused by a nil receiver to an Error
+	or String method, however, the output is the undecorated
+	string, "<nil>".
 
 	Scanning