diff --git a/src/time/time.go b/src/time/time.go
index 5283b7e..ff016a6 100644
--- a/src/time/time.go
+++ b/src/time/time.go
@@ -81,8 +81,11 @@
 //
 // Programs using times should typically store and pass them as values,
 // not pointers. That is, time variables and struct fields should be of
-// type time.Time, not *time.Time. A Time value can be used by
-// multiple goroutines simultaneously.
+// type time.Time, not *time.Time.
+//
+// A Time value can be used by multiple goroutines simultaneously except
+// that the methods GobDecode, UnmarshalBinary, UnmarshalJSON and
+// UnmarshalText are not concurrency-safe.
 //
 // Time instants can be compared using the Before, After, and Equal methods.
 // The Sub method subtracts two instants, producing a Duration.